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Great Smoky Mountains National Park

Great Smoky Mountains National Park is an American national park in the southeastern United States, with parts in North Carolina and Tennessee. The park straddles the ridgeline of the Great Smoky Mountains, part of the Blue Ridge Mountains, which are a division of the larger Appalachian Mountain chain. The park contains some of the highest mountains in eastern North America, including Clingmans Dome, Mount Guyot, and Mount Le Conte. The border between the two states runs northeast to southwest through the center of the park. The Appalachian Trail passes through the center of the park on its route from Georgia to Maine. With 13 million visitors in 2023, the Great Smoky Mountains National Park is the most visited national park in the United States.

The park encompasses 522,419 acre, making it one of the largest protected areas in the eastern United States. The main park entrances are located along U.S. Highway 441 (Newfound Gap Road) in Gatlinburg, Tennessee, and Cherokee, North Carolina, and also in Townsend, Tennessee. The park is internationally recognized for its mountains, waterfalls, biodiversity, and forests. In addition, the park preserves multiple historical structures that were part of communities occupied by early European-American settlers of the area.

The park was chartered by the United States Congress in 1934 and officially dedicated by President Franklin D. Roosevelt in 1940. The Great Smoky Mountains was the first national park having land and other costs paid in part with federal funds; previous parks were funded wholly with state money or private funds. The park was designated as a UNESCO World Heritage Site in 1983 and an International Biosphere Reserve in 1988.

The park anchors a large tourism industry based in Sevier County, Tennessee, adjacent to the park. Major attractions include Dollywood, the second-most visited tourist attraction in Tennessee, Ober Gatlinburg, and Ripley's Aquarium of the Smokies. Tourism to the park contributes an estimated $2.5 billion annually into the local economy.

Geography
The Great Smoky Mountains National Park covers a total of 522,419 acre The park is roughly evenly divided between Tennessee and North Carolina, and is located within portions of Blount, Sevier, and Cocke Counties in Tennessee, and Swain and Haywood Counties in North Carolina. The park borders an Indian reservation to the south that is home to the Eastern Band of Cherokee Indians, a federally-recognized tribe who are descended from a small group of Cherokee who evaded the forced migration of the Cherokee people to present-day Oklahoma. The town of Gatlinburg is located directly north of the park. Other cities and towns adjacent to the park include Townsend in Tennessee and Bryson City, Fontana Dam, and Maggie Valley in North Carolina. The Cherokee National Forest borders the park to the east and west in Tennessee, and the Nantahala National Forest borders much of the park in North Carolina.

Mountains
The Great Smoky Mountains National Park protects the majority of the Great Smoky Mountains, a subrange of the Blue Ridge Mountains, which are a subrange of the Appalachian Mountains. The range runs roughly east to west, nestled between the Bald Mountains to the east, the Plott Balsams to the south, and the Unicoi Mountains to the west. The park also protects a small portion of foothills, which separate the range from the Ridge-and-Valley Appalachians to the north. From west to east, the range gradually widens, with most of the highest mountains located in the eastern half. Elevations in the park range from about 875 ft to 6643 ft at the summit of Clingmans Dome.

Clingmans Dome is the highest mountain in Tennessee and the third-highest mountain east of the Mississippi River. The park contains 16 of the "Southern Sixers"; mountains in Tennessee and North Carolina that reach elevations higher than 6000 ft. The second highest mountain in the park is Mount Guyot, at an elevation of 6,621 ft. Mount Le Conte, at an elevation of 6,593 ft, rises 5,301 ft from its base to its summit, making it the tallest mountain in the United States east of the Rocky Mountains.

Nestled between the mountains are a number of deep valleys, some of which are known as coves. The largest and most prominent is Cades Cove, a broad, flat plain situated between the main range and some of the foothills. Other major valleys include The Sugarlands, Greenbrier, Ocanaluftee, Cataloochee, Elkmont, Tremont, and Deep Creek. These valleys are among the most accessible areas of the park, and are often used as reference points for major areas within the park.

Streams and waterfalls
The Great Smoky Mountains National Park is located entirely within the Tennessee Valley, the watershed of the Tennessee River, and contains an estimated 2,900 mi of streams. The Little Tennessee River runs along the southwestern border of the park, which is impounded by Chilhowee Dam, Calderwood Dam, Cheoah Dam, and Fontana Dam along the boundary. The Pigeon River flows through a deep gorge near the eastern boundary of the park, separating the range from the Bald Mountains to the east. The Plott Balsams border the range to the south. Several smaller rivers have their source in the park, including the three prongs of the Little Pigeon River, the Oconaluftee River, and the Little River. Other major streams include Hazel Creek and Eagle Creek in the southwest, Raven Fork near Oconaluftee, Cosby Creek near Cosby, and Roaring Fork near Gatlinburg. More than 100 prominent waterfalls are located within the park. The tallest is Ramsey Cascades, located at the base of Mt. Guyot. This waterfall drops 100 ft over rock outcroppings into a small pool below. Rainbow Falls is the tallest single-drop waterfall, plunging 80 ft along LeConte Creek. Other popular waterfalls include Grotto Falls, Laurel Falls, Abrams Falls, Mingo Falls, Mouse Creek Falls, and Hen Wallow Falls.

Historic areas
The park service maintains four historic districts and one archaeological district within park boundaries, as well as nine individual listings on the National Register of Historic Places. Notable structures not listed include the Mountain Farm Museum buildings at Oconaluftee and buildings in the Cataloochee area. The Mingus Mill (in Oconaluftee) and Smoky Mountain Hiking Club cabin in Greenbrier have been deemed eligible for listing.

 * Historic districts
 * Cades Cove Historic District
 * Elkmont Historic District
 * Oconaluftee Archaeological District
 * Noah Ogle Place
 * Roaring Fork Historic District

 * Individual listings
 * Alex Cole Cabin
 * Clingmans Dome Observation Tower
 * Hall Cabin (in Hazel Creek area)
 * John Messer Barn
 * John Ownby Cabin
 * Oconaluftee Baptist Church (also called Smokemont Baptist Church)
 * Tyson McCarter Place
 * Mayna Treanor Avent Studio
 * Little Greenbrier School
 * Walker Sisters Place

Geology
The majority of rocks in the Great Smoky Mountains National Park are late Precambrian rocks that are part of the Ocoee Supergroup. This group consists of metamorphosed sandstones, phyllites, schists, and slate. Early Precambrian rocks are not only the oldest rocks in the park but also the dominant rock type in sites such as the Raven Fork valley and upper Tuckasegee River between Cherokee and Bryson City. They primarily consist of metamorphic gneiss, granite, and schist. Cambrian sedimentary rocks can be found among the bottom of the foothills to the northwest, and in limestone coves. One of the most visited attractions in the mountains is Cades Cove, which is a window or an area where older rocks made out of sandstone surround the valley floor of younger rocks made out of limestone.

The oldest rocks in the Smokies are the Precambrian gneiss and schists which were formed over a billion years ago from the accumulation of marine sediments and igneous rock. In the late Precambrian, the primordial ocean expanded, and the more recent Ocoee Supergroup rocks formed from the accumulation of eroding land mass onto the continental shelf. In the Paleozoic era, the ocean deposited a thick layer of marine sediments which left behind sedimentary rock. During the Ordovician period, the collision of the North American and African tectonic plates initiated the Alleghenian orogeny that created the Appalachian range. During the Mesozoic era rapid erosion of softer sedimentary rocks re-exposed the older Ocoee Supergroup formations.

Around 20,000 years ago, subarctic glaciers advanced southward across North America, and although they never reached the Smokies, the advancing glaciers led to colder mean annual temperatures and an increase in precipitation throughout the range. Trees were unable to survive at the higher elevations and were replaced by tundra vegetation. Spruce-fir forests occupied the valleys and slopes below approximately 4950 ft. The persistent freezing and thawing during this period created the large blockfields that are often found at the base of large mountain slopes.

Climate
According to the Köppen climate classification system, Great Smoky Mountains National Park has two climate types: humid subtropical (Cfa), and temperate oceanic (Cfb). The plant hardiness zone at Clingmans Dome Visitor Center is 5b with an average annual extreme minimum temperature of -14.3 F. Ascending the mountains is comparable to a trip from Tennessee to Canada.

The humid, subtropical air mass typically in place over the Smoky Mountains, coupled with orographic lift, produces large amounts of precipitation. Annual precipitation amounts range from 50-80 in, with heavy winter snowfall in the higher elevations. Flash flooding often occurs after heavy rain.

The average temperature difference between the mountains, such as Newfound Gap at 5048 ft above MSL, and the valleys at about 1600 ft, is between 10-13 F-change for highs, and between 3-6 F-change for lows. The difference between high temperatures is similar to the moist adiabatic lapse rate of 3.3 F-change per 1000 ft, while the smaller difference between low temperatures is the result of frequent temperature inversions developing in the morning, most often in autumn.

Strong damaging winds of 80-100 mph or higher occur a few times each year around the Smoky Mountains, mainly during the cool season from October to April, as a result of a phenomenon known as mountain waves. Mountain waves are strongest in a narrow area along the foothills and can create extensive areas of fallen trees and roof damage, especially around Cades Cove and Cove Mountain. Strong winds created by mountain waves were a contributing factor in the devastating Gatlinburg fire on November 28, 2016, during the 2016 Great Smoky Mountains wildfires. Damaging winds can also be generated by strong thunderstorms, with tornadoes and strong thunderstorm complexes (also known as mesoscale convective systems) occasionally affecting the Smoky Mountains.

Air pollution
The park is affected by air pollution because of increased development nearby. In a 2004 report by the National Parks Conservation Association, Great Smoky Mountains National Park was considered the most polluted national park. From 1999 to 2003, the park recorded approximately 150 unhealthy air days, the equivalent of about one month of unhealthy air days per year. In 2013, Colorado State University reported that, with the passing of the United States Clean Air Act in 1970 and the subsequent implementation of the Acid Rain Program, there had been a "significant improvement" to the air quality in the Great Smoky Mountains from 1990 to 2010. With steady improvements in noxious emissions, visibility in the park on the haziest days has improved from an average of 9 miles in 1998 to 40 miles in 2018. A report published in 2023 by the North Carolina Division of Air Quality indicates significant drops in emissions of sulfur dioxide, carbon monoxide, oxides of nitrogen, volatile organic compounds, and fine particulate matter.

Biology and ecology
The Great Smoky Mountains National Park is the most biologically diverse national park in the United States. About 19,000 species of organisms are known to live in the park, and scientists estimate that as many as 80,000 to 100,000 additional species may also be present. The land now protected by the park became a refuge for plants and animals that were displaced during the Last Glacial Period. The immense biodiversity is also supported by the rainy and temperate climate. No other location of similar size within a temperate climate is known to match the park's biodiversity.

Flora
Forests cover approximately 95 percent of the Great Smoky Mountains National Park. The lower region forests are dominated by deciduous leafy trees. At higher altitudes, deciduous forests give way to coniferous trees like Fraser fir. An estimated 20 to 25 percent of the forests in the park are estimated to be old-growth forest, with many trees that predate European settlement of the area. This is one of the largest blocks of deciduous, temperate, old growth forest in North America. Most of the forest is a mature second-growth hardwood forest. The variety of elevations, the abundant rainfall, and the presence of old growth forests give the park an unusual richness of biota. The park is home to over 1,500 species of flowering plants, more than in any other national park in North America. These include 35 kinds of delicate orchids, 27 violets, and 58 members of the lily family. The park contains 101 species of native trees and 114 species of native shrubs. The park also contains over 490 species of non-vascular plants. More than 4,000 species of non-flowering plants, 2,700 fungi, 952 algae, and 563 lichen species are found in the park. Plants and animals common in the country's Northeast have found suitable ecological niches in the park's higher elevations, while southern species find homes in the balmier lower reaches.

The forests of the Smokies are typically divided into three zones—The cove hardwood forests in the stream valleys, coves, and lower mountain slopes; the northern hardwood forests on the higher mountain slopes; and the spruce-fir or boreal forest at the very highest elevations. Appalachian balds—patches of land where trees are unexpectedly absent or sparse—are interspersed through the mid-to-upper elevations in the range. Balds include grassy balds and heath balds. Heath balds are covered mostly in shrubbery that is part of the heath family such as rhododendron and mountain laurel. They are primarily found in the northeastern part of the park on narrow ridges at elevations between 3,600 and 5,200 ft. Grass balds are mountaintop meadows that are mostly covered in grasses and sedges. They are typically found on rounded mountaintops or slopes in the southwestern part of the park at elevations ranging from 4,500 to 5,700 ft. Mixed oak-pine forests are found on dry ridges, especially on the south-facing North Carolina side of the range.

Cove hardwood forest

Cove hardwood forests, which are native to southern Appalachia, are among the most diverse forest types in North America. The cove hardwood forests of the Smokies are mostly second-growth, although some 72000 acre are still old-growth. They are found in the valleys between mountain ridges at elevations below 4,500 ft in deep moist soil. The Albright Grove along the Maddron Bald Trail (between Gatlinburg and Cosby) is an accessible old-growth forest with some of the oldest and tallest trees in the entire range.

Over 130 species of trees are found among the canopies of the cove hardwood forests in the Smokies. The dominant species include yellow birch (Betula alleghaniensis), basswood (Tilia americana), yellow buckeye (Aesculus flava), tulip tree (Liriodendron tulipifera; commonly called "tulip poplar"), silverbells (Halesia carolina), sugar maple (Acer saccharum), cucumber magnolia (Magnolia acuminata), shagbark hickory (Carya ovata), Carolina hemlock (Tsuga caroliniana) and eastern hemlock (Tsuga canadensis). The American chestnut (Castanea dentata), which was arguably the most beloved tree of the range's pre-park inhabitants, was killed off by the introduced Chestnut blight in the early-to-mid 20th century.

The understories of the cove hardwood forest contain dozens of species of shrubs and vines. Dominant species in the Smokies include the Eastern redbud (Cercis canadensis), flowering dogwood (Cornus florida), Catawba rhododendron (Rhododendron catawbiense), mountain laurel (Kalmia latifolia), and smooth hydrangea (Hydrangea arborescens).

Northern hardwood forest

The mean annual temperatures in the higher elevations in the Smokies are cool enough to support forest types more commonly found in the northern United States. The northern hardwood forests constitute the highest broad-leaved forest in the eastern United States. About 28600 acre are old-growth.

In the Smokies, the northern hardwood canopies are dominated by yellow birch (Betula alleghaniensis) and American beech (Fagus grandifolia). White basswood (Tilia heterophylla), mountain maple (Acer spicatum) and striped maple (Acer pensylvanicum), and yellow buckeye (Aesculus flava) are also present. The understory is home to diverse species such as coneflower, skunk goldenrod, Rugels ragwort, bloodroot, hydrangea, and several species of grasses and ferns.

A unique community is the beech gap, or beech orchard. Beech gaps consist of high mountain gaps that have been monopolized by beech trees. The beech trees are often twisted and contorted by the high winds that occur in these gaps. Why other tree types such as the red spruce fail to encroach into the beech gaps is unknown.

Spruce-fir forest

The Southern Appalachian spruce–fir forest—also called the "boreal" or "Canadian" forest—is a relict of the ice ages, when mean annual temperatures in the Smokies were too cold to support a hardwood forest. While the rise in temperatures between 12,500 and 6,000 years ago allowed the hardwoods to return, the spruce-fir forest has managed to survive on the harsh mountain tops, typically above 5500 ft. About 10600 acre of the spruce-fir forest are old-growth.

The spruce-fir forest consists primarily of two conifer species—red spruce (Picea rubens) and Fraser fir (Abies fraseri). The Fraser firs, which are native to southern Appalachia, once dominated elevations above 6200 ft in the Smokies. Most of these firs were killed, however, by an infestation of the balsam wooly adelgid, which arrived in the Smokies in the early 1960s. Thus, red spruce is now the dominant species in the range's spruce-fir forest. Large stands of dead Fraser firs remain atop Clingmans Dome and on the northwestern slopes of Old Black. While much of the red spruce stands were logged in the 1910s, the tree is still common throughout the range above 5500 ft. Some of the red spruces are believed to be 300 years old, and the tallest rise to over 100 ft.

The main difference between the Southern Appalachian spruce–fir forest and the spruce-fir forests in northern latitudes is the dense broad-leaved understory of the former, which are home to catawba rhododendron, mountain ash, pin cherry, thornless blackberry, and hobblebush. The herbaceous and litter layers are poorly lit year-round and are thus dominated by shade-tolerant plants such as ferns, namely mountain wood fern and northern lady fern, and over 280 species of mosses.

Wildflowers

The Great Smoky Mountains National Park has over 1,400 flowering plant species. Many wildflowers grow in mountains and valleys, including bee balm, Solomon's seal, Dutchman's breeches, various trilliums, the Dragon's Advocate and even hardy orchids. There are two native species of rhododendron in the area. The catawba rhododendron has purple flowers in May and June, while the rosebay rhododendron has longer leaves and white or light pink blooms in June and July.

The orange- to sometimes red-flowered and deciduous flame azalea closely follows along with the catawbas. The closely related mountain laurel blooms in between the two, and all of the blooms progress from lower to higher elevations. The reverse is true in autumn, when nearly bare mountaintops covered in rime ice (frozen fog) can be separated from green valleys by very bright and varied leaf colors. The rhododendrons are broadleafs, whose leaves droop in order to shed wet and heavy snows that come through the region during winter.

Fauna
The Great Smoky Mountains National Park is home to 65 species of mammals, over 240 species of birds, 43 species of amphibians, 67 species of fish, 40 species of reptiles, and 43 species of amphibians.

Mammals
The American black bear is perhaps the best known animal that resides within the Great Smoky Mountains National Park, and has come to symbolize wildlife in the park, frequently appearing on the covers of the park's literature. The range has the densest American black bear population east of the Mississippi River. Most of the range's adult black bears weigh between 100 lb and 300 lb, although some weighing as much as 600 lb have been documented in the park. An estimated 1,900 black bears reside in the park, although the exact figure is variable.

The Smokies are home to 27 species of rodents, including the North American beaver, woodchucks, chipmunks, two species of squirrel and skunk, and the endangered northern flying squirrel. 12 species of bats, including the endangered Indiana bat and Rafinesque's big-eared bat, are found within the park. Other mammals include the white-tailed deer, the population of which drastically expanded with the creation of the national park. The bobcat is the only remaining wild cat species, although sightings of cougars, which once thrived in the area, are still occasionally reported. Raccoons, which are the state wild animal of Tennessee, are plentiful in the park. The Virginia opossum, the only marsupial in North America, is found in the park. The coyote is not believed to be native to the range but has moved into the area in recent years and is treated as a native species. Two species of fox, the red fox and the gray fox, are found within the Smokies, with the former being documented at all elevations.

An attempt to reintroduce red wolves into the park in 1991 failed drastically, forcing the U.S. Fish and Wildlife Service to remove the wolves from the area in 1998. These wolves were relocated to the Alligator River National Wildlife Refuge in North Carolina. North American river otters were reintroduced to the park in phases between 1986 and 1994. Elk were reintroduced to the park in 2001 and 2002. Today they are most abundant in the Cataloochee area in the southeastern section of the park. European wild boar, introduced as game animals in the early 20th century, thrive in southern Appalachia but are considered a nuisance because of their tendency to root up and destroy plants. The boars are seen as taking food resources away from bears as well, and the park service has sponsored a program that pays individuals to hunt and kill boars and leave their bodies in locations frequented by bears.

Birds

The Smokies are home to a diverse bird population due to the presence of multiple forest types. Nearly 120 bird species are known to use the park as a breeding ground, including 52 from the neotropics and additional ones from northern climatic regions. Other migratory species use the park as a stopover and for foraging for food. Species that thrive in southern hardwood forests, such as the red-eyed vireo, wood thrush, wild turkey, northern parula, ruby-throated hummingbird, and tufted titmouse, are found throughout the lower elevations and cove hardwood forests. Species more typical of cooler climates, such as the raven, winter wren, black-capped chickadee, yellow-bellied sapsucker, dark-eyed junco, and Blackburnian, chestnut-sided, and Canada warblers, are found in the spruce-fir and northern hardwood zones. Ovenbirds, whip-poor-wills, and downy woodpeckers live in the drier pine-oak forests and heath balds. Bald eagles and golden eagles have been spotted at all elevations in the park. Peregrine falcon sightings are also not uncommon, and a peregrine falcon eyrie is known to have existed near Alum Cave Bluffs throughout the 1930s. Red-tailed hawks, the most common hawk species, have been sighted at all elevations. Owl species include the barred owl, eastern screech owl, and northern saw-whet owl.

Reptiles and amphibians
The Great Smoky Mountains National Park is home to one of the world's most diverse salamander populations, and is known as the "Salamander Capital of the World". Five of the world's nine families of salamanders are found in the range, consisting of up to 31 species. The red-cheeked salamander is found only in the Smokies. The imitator salamander is found only in the Smokies and the nearby Plott Balsams and Great Balsam Mountains. Two other species—the southern gray-cheeked salamander and the southern Appalachian salamander—occur only in the general region. Other species include the shovelnose salamander, blackbelly salamander, eastern red-spotted newt, and spotted dusky salamander. The hellbender inhabits swift streams, and can grow to 29 in in length. A total of 14 frog and toad species found within the park include the American toad and the American bullfrog, wood frog, upland chorus frog, northern green frog, and spring peeper.

Reptiles found within the park include eight species of turtles, nine species of lizards, and 23 species of snakes. 21 of these snake species are from the family Colubridae, and include multiple kingsnakes, the black rat snake, the northern water snake, and the corn snake. Timber rattlesnakes—one of two venomous snake species in the Smokies—are found at all elevations. The other venomous snake, the copperhead, is typically found at lower elevations. Both of these snakes are pit vipers. The eastern box turtle, which is the state reptile of North Carolina and Tennessee, is the most common turtle in the park, and is mostly terrestrial, but is usually found near waterways. Important lizards found within the park include the eastern fence lizard, green anole, and multiple species of skinks. The rarest lizard in the park is the eastern slender glass lizard, a legless lizard often mistaken for a snake.

Fish and insects
Fish include trout, lamprey, darter, shiner, bass, minnows, and sucker. An estimated 1,073 mi of streams in the park support fish. The brook trout is the only trout species native to the range, although northwestern rainbow trout and European brown trout were introduced in the first half of the 20th century. The larger rainbow and brown trout outcompete the native brook trout for food and habitat at lower elevations. As such, most of the brook trout found in the park today are in streams above 3,000 feet in elevation where temperatures are typically below 61 F. Trout are generally smaller than in different locales, due to a low density of food. Four protected fish species–the smoky madtom, yellowfin madtom, spotfin chub, and duskytail darter–are found in the park. Other prominent fish species include the American gizzard shad, lamoetra appendix, longnose gar, and mountain brook lamprey.

More than 9,000 species of insects have been documented in the park. The most abundant insect groups include butterflies, moths, beetles, flies, wasps, bees, and ants. These insects serve a crucial role pollinating plants and aiding in the decomposition of wood. The firefly Photinus carolinus, whose synchronized flashing light displays occur in mid-June, is native to the Great Smoky Mountains with a population epicenter near Elkmont, Tennessee. This firefly is sometimes referred to as a "celebrity insect" due to the large numbers of visitors who come to view its light displays.

Attractions and activities
The Great Smoky Mountains National Park is a major tourist attraction in the region. It has been the most visited national park for many years, with over 14.1 million recreational visitors (tourists) in 2021. The recreational figure represents nearly twice as many tourists as the Grand Canyon, which received nearly 6 million visitors the same year. Surrounding towns—notably Gatlinburg, Pigeon Forge, Sevierville, and Townsend in Tennessee, and Cherokee, Sylva, Maggie Valley, and Bryson City in North Carolina—receive a significant portion of their income from tourism associated with the park.

The park features three main entrances, located in Gatlinburg, Cherokee, and Townsend. Entrance into the park is free, while there is a fee for parking. U.S. Route 441 (US 441, Newfound Gap Road) is the main road through the park, and runs between Cherokee and Gatlinburg. The Gatlinburg entrance to the park is the busiest, and is also the southern terminus of the Great Smoky Mountains Parkway, a highway which connects the park to Pigeon Forge, Sevierville, and Interstate 40 to the north. The two main visitor centers inside the park are the Sugarlands Visitors' Center near the Gatlinburg entrance and the Oconaluftee Visitor Center near the Cherokee entrance. These visitor centers also contain ranger stations, and provide exhibits on wildlife, geology, and the history of the park. They also sell books, maps, and souvenirs. Little River Gorge road, which runs along the Little River and connects to US 441 at the Sugarlands Visitor Center.

Hiking and trails

There are 850 mi of trails and unpaved roads in the park for hiking.

A total of the 71.6 mi of the Appalachian Trail (AT) are located within the park. The AT enters the park atop Fontana Dam, and ascends a long ridge to the top of Brier Lick Knob at the Tennessee-North Carolina state line. The trail then roughly follows the crest of the range and the state line for its remainder in the park, rarely dropping below 5,000 ft. Clingmans Dome is the highest point along the entire trail. Other notable summits that the AT traverses include Thunderhead Mountain, Silers Bald, Mount Collins, Newfound Gap, Mount Kephart, Charlies Bunion, Mount Sequoyah, Mount Chapman, Mount Guyot, Old Black, and Mount Cammerer. A total of 12 trail shelters are located along the Appalachian Trail in the park, which are used mostly for extended backpacking trips.

Mount Le Conte is one of the most frequented destinations in the park, with a total of five trails leading to its summit. The most heavily traveled is the Alum Cave Trail. It provides many scenic overlooks and unique natural attractions such as Alum Cave Bluffs and Arch Rock. The Bullhead and Rainbow Falls trails each climb approximately 4,000 ft, making them two of the trails with the largest net elevation gain east of the Mississippi River. Hikers may spend a night at the LeConte Lodge, located near the summit, which provides cabins and rooms for rent except during the winter season. Accessible solely by trail, it is the only private lodging available inside the park, and the highest inn in the eastern United States. The Mt. LeConte Shelter is located atop the mountain on The Boulevard Trail. It can accommodate 12 people per night and is the only backcountry site in the park that has a permanent ban on campfires.

Another popular hiking trail leads to the pinnacle of the Chimney Tops, so named because of its unique dual-humped peaktops. This short but strenuous trek rewards nature enthusiasts with a spectacular panorama of the surrounding mountain peaks. It was the flashpoint for the 2016 Great Smoky Mountains wildfires, and therefore sustained extensive damage, evident still today in clearly visible burn scars. The extreme heat of the fires resulted in accelerated weathering and potential mass wasting of the exposed rock, and therefore access to the summit is no longer permitted for safety reasons.

Both the Laurel Falls and Clingmans Dome trails offer relatively easy, short, paved paths to their respective destinations. The Laurel Falls Trail leads to a powerful 80 ft waterfall.

In addition to day hiking, the national park offers opportunities for backpacking and camping. Camping is allowed only in designated camping areas and shelters. There are three shelters in the park that are not located on the Appalachian Trail. The Kephart Shelter is located at the terminus of the Kephart Prong Trail which begins upstream of the Collins Creek Picnic Area. The shelter, situated along a tributary of the Oconaluftee River can accommodate 14 people. Laurel Gap Shelter is one of the more remote shelters in the park. Situated in a beech forest swag between Balsam High Top and Big Cataloochee Mountain, the Laurel Gap Shelter can accommodate up to 14 people per night. This shelter is a popular base camp for peakbaggers exploring the heart of the Smokies wilderness.

Sightseeing
The most frequented destination in the Great Smoky Mountains National Park is Cades Cove, a cleared valley that provides dramatic views of the surrounding mountains. Cades cove has numerous preserved historic buildings including log cabins, barns, and churches. Cades Cove is the single most frequented destination in the national park. An 11 mi one-way loop road encircles Cades Cove. Self-guided automobile and bicycle tours offer the many sightseers a glimpse into the way of life of old-time southern Appalachia. Other historical areas within the park include Roaring Fork, Cataloochee, Elkmont, and the Mountain Farm Museum and Mingus Mill in Oconaluftee.

U.S. Route 441 (Newfound Gap Road) providing automobile access to many trailheads and overlooks, most notably that of Newfound Gap. At an elevation of 5048 ft, it is the lowest gap in the crest of the mountains and is situated near the center of the park, on the Tennessee/North Carolina state line, halfway between Gatlinburg and Cherokee. It was here that in 1940, from the Rockefeller Memorial, Franklin Delano Roosevelt dedicated the national park. On clear days Newfound Gap offers arguably the most spectacular scenes accessible via highway in the park. A 45 ft observation tower is located atop Clingmans Dome, and is accessible via a 1/2 mi trail that connects to a parking area and overlook. The tower provides a 360 degree view over the Tennessee, North Carolina, and Georgia mountains. On a clear day, visibility can range as far as 100 mi, but is often limited to 20 mi by air pollution.

In addition to Newfound Gap Road and Cades Cove, a number of additional scenic drives and overlooks are found throughout the park. Lakeview Drive, located along the north shore of Fontana Lake, is a scenic road that was never completed. Split in two segments, it is accessible via either Fontana Dam or Bryson City. It features an unused road tunnel and connects to various hiking and horseback riding trails in the area. The Foothills Parkway is a scenic parkway maintained by the park that was also never completed. It consists of two noncontiguous segments located to the northwest and northeast of the park, respectively. The foothills parkway traverses a number of high ridges in the foothills of the Great Smoky Mountains, and provides unobstructed views of the mountains to the south, as well as the Tennessee Valley to the north. The southern terminus of the Blue Ridge Parkway is located on the edge of the park in Cherokee. The Gatlinburg Bypass provides scenic views of the mountains that rise around Gatlinburg.

Other activities
After hiking and simple sightseeing, fishing (especially fly fishing) is the most popular activity in the national park. The park's waters have long had a reputation for healthy trout activity as well as challenging fishing terrain. Brook trout are native to the waters, while both brown and rainbow were introduced to the area. There are strict regulations regarding how fishing may be conducted. Horseback riding (offered by the national park and on limited trails), bicycling (available for rent in Cades Cove) and water tubing are all also practiced within the park. Many of the roads in the park, are popular with motorists and car enthusiasts. A section of U.S. Route 129 which runs along the western boundary of the park is known as the "Tail of the Dragon", due to its extremely curvy alignment, and is popular with motorcyclists and sports car enthusiasts.

Designated backcountry campsites are scattered throughout the park. A permit, available at ranger stations and via the park website, is required for all backcountry camping. Additionally, reservations are required for all of the shelters and backcountry campsites. A maximum stay of one night, in the case of shelters, or three nights, in the case of campsites, may limit the traveler's itinerary.

From late May to early June, the Elkmont area of the park hosts the peak display period for synchronous fireflies (Photinus carolinus), one of at least 19 species of fireflies that live in the park. They are the only species in America whose individuals can synchronize their flashing light patterns.

Prehistory
Native Americans had likely been hunting in the Great Smoky Mountains for 14,000 years. Numerous Archaic period (c. 8000–1000 B.C.) artifacts have been found within the national park's boundaries, including projectile points uncovered along likely animal migration paths. Woodland period (c. 1000 B.C. - 1000 A.D.) sites found within the park contained 2,000-year-old ceramics and evidence of primitive agriculture.

The increasing reliance upon agriculture during the Mississippian period (c. 900–1600 A.D.) lured Native Americans away from the game-rich forests of the Smokies and into the fertile river valleys on the outer fringe of the range. Substantial Mississippian-period villages were uncovered at Citico and Toqua (named after the Cherokee villages that later thrived at these sites) along the Little Tennessee River in the 1960s. Fortified Mississippian-period villages have been excavated at the McMahan Indian Mounds in Sevierville and as well as mounds in Townsend.

Most of these villages were part of a minor chiefdom centered on a large village known as Chiaha, which was located on an island now submerged by Douglas Lake. The 1540 expedition of Hernando de Soto and the 1567 expedition of Juan Pardo passed through the French Broad River valley north of the Smokies, both spending a considerable amount of time at Chiaha. The Pardo expedition followed a trail across the flanks of Chilhowee Mountain to the Mississippian-period villages at Chilhowee and Citico (Pardo's notary called them by their Muskogean names, "Chalahume" and "Satapo").

Cherokee
In the latter 17th century, the Cherokee began migrating into what is now eastern Tennessee and western North Carolina from what is now Virginia, possibly to escape expanding European settlement and diseases in the north. By the time the first European settlers arrived, the Cherokee controlled much of the region, and the Great Smoky Mountains lay at the center of their territory. They called the range Shaconage, meaning "place of blue smoke". One Cherokee legend tells of a magical lake called Atagahi hidden deep within the range but inaccessible to humans. Another tells of a captured Shawnee medicine man named Aganunitsi who, in exchange for his freedom, travels to the remote sections of the range in search of the Uktena. The Cherokee called Gregory Bald Tsitsuyi ᏥᏧᏱ, or "rabbit place," and believed the mountain to be the domain of the Great Rabbit. Other Cherokee place names in the Smokies included Duniskwalgunyi ᏚᏂᏍᏆᎫᏂ, or "forked antlers", which refers to the Chimney Tops, and kuwahi ᎫᏩᎯ, or "mulberry place", which refers to Clingmans Dome.

Most Cherokee settlements were located in the river valleys on the outer fringe of the Smokies, which along with the Unicoi Mountains, provided the main bulwark dividing the Overhill Cherokee villages in modern-day Tennessee from the Cherokee Middle towns in present-day North Carolina. The Overhill town of Chilhowee was situated at the confluence of Abrams Creek and the Little Tennessee, and the Overhill town of Tallassee was located just a few miles upstream near modern Calderwood (both village sites are now under Chilhowee Lake). A string of Overhill villages, including Chota and Tanasi, dotted the Little Tennessee valley north of Chilhowee. The Cherokee Middle towns included the village of Kittowa (which the Cherokee believed to be their oldest village) along the Tuckasegee River near Bryson City. The village of Oconaluftee, which was situated along the Oconaluftee River near the modern Oconaluftee Visitor Center, was the only known permanent Cherokee village located within the national park's boundaries. Sporadic or seasonal settlements were located in Cades Cove and the Hazel Creek valley.

European exploration and settlement and Cherokee removal
European explorers and settlers began arriving in Western North Carolina and East Tennessee in the mid-18th century. The influx of settlers at the end of the French and Indian War brought conflict with the Cherokee, who still held legal title to much of the land. When the Cherokee aligned themselves with the British at the outbreak of the American Revolution in 1776, American forces launched an invasion of Cherokee territory. The Middle towns, including Kittuwa, were burned by General Griffith Rutherford, and several of the Overhill towns were burned by John Sevier. By 1805, the Cherokee had ceded control of the Smokies to the U.S. government. Although much of the tribe was forced west along the Trail of Tears in 1838, a few—largely through the efforts of William Holland Thomas—managed to retain their land on the Qualla Boundary and today comprise the Eastern Band of Cherokee Indians.

In the 1780s, several frontier outposts had been established along the outskirts of the Smokies, namely Whitson's Fort in what is now Cosby and Wear's Fort in what is now Pigeon Forge. Permanent settlers began arriving in these areas in the 1790s. John Mingus, who built the Mingus Mill, and Ralph Hughes settled on the Oconaluftee in 1795. Other settlers soon followed and began clearing land and farming. In 1801, the Whaley brothers, William and John, moved from North Carolina to become the first settlers in what is now the Greenbrier section of the park. In 1802, Edgefield, South Carolina, resident William Ogle arrived in White Oak Flats where he cut and prepared logs for cabin construction. Although Ogle died shortly after returning to Edgefield, his wife, Martha Jane Huskey, eventually returned with her family and several other families to White Oak Flats, becoming the first permanent settlers in what would eventually become Gatlinburg. Their children and grandchildren spread out southward into the Sugarlands and Roaring Fork areas. Cades Cove was settled largely by families who had purchased lots from land speculator William "Fighting Billy" Tipton. The first of these settlers, John and Lucretia Oliver, arrived in 1818. After 1821, more families settled in Cades Cove including the Jobes, Gregorys, Sparkes, and Cables. As the community began to grow, the Cades Cove Baptist Church was established in 1827. Two Cades Cove settlers, Moses and Patience Proctor, crossed over to the North Carolina side of the Smokies in 1836 to become the first European American settlers in the Hazel Creek area. The Cataloochee area was first settled by the Caldwell family, who migrated to the valley in 1834.

Like most of southern Appalachia, the early 19th century economy of the Smokies relied on subsistence agriculture. The average farm consisted of roughly 50 acre, part of which was cultivated and part of which was woodland. Early settlers lived in 16 ft x 20 ft log cabins, although these were replaced by more elaborate log houses and eventually, as lumber became available, by modern frame houses. Most farms included at least one barn, a springhouse (used for refrigeration), a smokehouse (used for curing meat), a chicken coop (protected chickens from predators), and a corn crib (kept corn dry and protected it from rodents). Some of the more industrious farmers operated gristmills, general stores, and sorghum presses. Religion was a central theme in the lives of the early residents of the Smokies, and community life was typically centered on churches. Christian Protestantism—especially Primitive Baptists, Missionary Baptists, Methodists, and Presbyterians; dominated the religious culture of the region. Particularly because of their pressure to acquire land in the Deep South, in 1830 President Andrew Jackson signed the Indian Removal Act, beginning the process that eventually resulted in the forced removal of all Native American tribes east of the Mississippi River to Indian Territory in present-day Oklahoma. Most of the Cherokee were removed in an event that became known as the Trail of Tears. For a period some Cherokees, led by such warriors as Tsali, evaded removal by staying in the area now part of the Great Smoky Mountains National Park. A band on the Oconaluftee River acquired land and also remained. Their descendants make up most of the federally recognized Eastern Band of Cherokee Indians, based in Cherokee, North Carolina, and their Qualla Boundary reserve to the south of the park.

American Civil War
While both Tennessee and North Carolina joined the Confederacy at the outbreak of the American Civil War in 1861, Union sentiment in the Great Smoky Mountains was much stronger relative to other regions in these two states. Generally, the communities on the Tennessee side of the Smokies supported the Union, while communities on the North Carolina side supported the Confederates. On the Tennessee side, 74% of Cocke Countians, 80% of Blount Countians, and 96% of Sevier Countians voted against secession. In the North Carolina Smokies—Cherokee, Haywood, Jackson, and Macon counties—about 46% of the population favored secession. This was largely due to the fact that slavery was rare in these regions, as the geography did not allow for large plantation complexes dependent on slave labor that came to dominate the economy of the antebellum south.

While no major engagements took place in the Smokies, minor skirmishes were fairly common. Cherokee chief William Holland Thomas formed a Confederate legion made up mostly of Cherokee soldiers. Thomas' Legion crossed the Smokies in 1862 and occupied Gatlinburg for several months to protect saltpeter mines atop Mount Le Conte. Residents of predominantly Union Cades Cove and predominantly Confederate Hazel Creek routinely crossed the mountains to steal one another's livestock. Residents of Cosby and Cataloochee did likewise. One notable Civil War incident was the murder of long-time Cades Cove resident Russell Gregory (for whom Gregory Bald is named), which was carried out by bushwhackers in 1864 shortly after Gregory had led an ambush that routed a band of Confederates seeking to wreak havoc in the cove. Another incident was George Kirk's raid on Cataloochee, in which Kirk killed or wounded 15 Union soldiers recovering at a makeshift hospital.

Logging and early preservation movements
While selective logging occurred in the Great Smoky Mountains throughout the 19th century, the general inaccessibility of the forests prevented major logging operations, and lumber firms initially relied on the lowland forests in the northeastern United States and the Mississippi Delta in the southeast. As timber resources in these regions became exhausted, and as the demand for lumber skyrocketed after the Civil War, entrepreneurs began looking for ways to reach the virgin forests of southern Appalachia. The first logging operations in the Smokies, which began in the 1880s, used splash dams or booms to float logs down rivers to lumber mills in nearby cities. Notable splash dam and boom operations included the English Lumber Company on Little River, the Taylor and Crate operations along Hazel Creek, and the ambitious operations of Alexander Arthur on the Pigeon River. All three of these operations failed within their first few years, however, after their dams and boom systems were destroyed by floods.

Innovations in logging railroads and band saw technology in the late 19th century made large-scale logging possible in the mountainous areas of southern Appalachia. The largest logging operation in the Smokies was the Little River Lumber Company, which logged the Little River watershed between 1901 and 1939. The firm constructed the Little River Railroad to haul timber out of the remote regions of the area, and established company towns at Townsend (named for the company's chief owner and manager, Col. Wilson B. Townsend), Elkmont, and Tremont. The Little River Railroad set an example for larger companies to also purchase land in the Smokies for logging. The second-largest logging operation was the Ritter Lumber Company, which logged the Hazel Creek watershed between 1907 and 1928. Ruins of Ritter's lumbering operations are still visible along the Hazel Creek Trail. Other lumbering operations included Three M Lumber and Champion Fibre, both of which logged the Oconaluftee watershed. Logging in the Smokies reached its peak in 1909, and by the time all operations ceased in the 1930s, logging firms had removed two-thirds of the virgin forests from the Smokies. According to the National Park Service, 80% of the Smokies was clear cut in the early 20th century.

Early tourism and park establishment
The idea for a national park in the southern Appalachians first reportedly arose in the late 19th century. In the early 20th century, locals began banding together to raise money for the preservation of the land, as its natural beauty was being destroyed by the cut-and-run-style clearcutting employed by the timber companies. Wilson B. Townsend, the head of Little River Lumber, began advertising Elkmont as a tourist destination in 1909. Within a few years, the Wonderland Hotel and the Appalachian Club had been established to cater to elite Knoxvillians seeking summer mountain getaways. When the National Park Service was established in 1916, they wanted a park in the eastern United States but did not have the funds to establish one at the time.

In the summer of 1923, Knoxville resident Anne May Davis envisioned a national park in the Great Smoky Mountains while visiting Yellowstone National Park. Davis shared her idea with her husband, Knoxville businessman W. P. Davis, who shared the idea with then-Secretary of Interior Hubert Work. Davis initially encountered difficulty in gaining support for the movement, but by the end of the year, worked with several Appalachian Club members, among them Knoxville businessman Colonel David C. Chapman; and the Knoxville Automobile Club to found the Great Smoky Mountains Conservation Association (GSMCA). In 1924, Secretary work established the Southern Appalachian National Park Committee to study the feasibility of a national park in the southern Appalachians. On July 30, 1924, a delegation from the GSMCA met with the Park Committee in Asheville, and presented a series of photographs of the park to the committee. This convinced members of the committee, many of whom favored a national park in the Grandfather Mountain–Linville Gorge area, to visit the Smokies and begin pursuing the range as a candidate for a national park. Knoxville Mayor Ben Morton, travel writer Horace Kephart, explorer Paul M. Fink, and photographers Jim Thompson and George Masa were also instrumental in fostering the development of the park. The movement was backed by automobile clubs, most of which were chapters of the American Automobile Association. In addition to preservation, supporters of the park also stressed the economic benefit of tourism.

On December 13, 1924, the Park Committee recommended the establishment of national parks in the Smokies and the Blue Ridge Mountains in Virginia, the latter of which would become Shenandoah National Park. In 1925, Tennessee Governor Austin Peay signed legislation authorizing the first land purchase for the park, and appointed Colonel Chapman chairman of the Tennessee State Park and Forestry Commission. He was largely responsible for raising funds for land purchases and coordinating park efforts between local, state, and federal entities. That same year, a lodge was established atop Mount Le Conte by hiker Paul Adams to entertain visiting dignitaries from Washington, D.C. President Calvin Coolidge signed legislation on May 22, 1926, which authorized the park, but there was no nucleus of federally owned land around which to develop it. In 1927, both states' legislatures established commissions to orchestrate land purchases and agreed to provide the first appropriations for these purchases, contingent on the remaining funds being raised from other sources. North Carolina provided $2 million (equivalent to $ in ) from the state's general fund, and Tennessee provided $1.5 million (equivalent to $ in ) which was funded by a special gasoline tax. Private citizens raised approximately $1 million (equivalent to $ in ), but struggled to raise the necessary funds until businessman and philanthropist John D. Rockefeller Jr. contributed $5 million (equivalent to $ in ) to the effort in March 1928.

The creation of the Great Smoky Mountains National Park proved much more complex than its predecessors in the west, which were largely concocted from federally owned land. Along with convincing logging firms to sell lucrative lumber rights, the park commissions had to negotiate the purchase of thousands of small farms and remove entire communities. Slowly, mountain homesteaders, miners, and loggers were evicted from their land. Farms and timbering operations were abolished to establish the protected areas of the park. Ben W. Hooper, who had served as Governor of Tennessee from 1911 to 1915, served as the principal land purchasing agent for the park. The park commissioners also had to deal with the Tennessee and North Carolina legislatures, which at times were opposed to spending taxpayer money on park efforts. In spite of these difficulties, the park commission had completed most major land purchases by 1932. During the Great Depression, the Civilian Conservation Corps, the Works Progress Administration, and other federal organizations hired workers to build trails, firetowers, roads, and other infrastructure in the park. The Great Smoky Mountains National Park was officially established by Congress on June 15, 1934. On September 2, 1940, President Franklin D. Roosevelt formally dedicated the park in a ceremony at the Rockefeller Memorial at Newfound Gap to a crowd of approximately 10,000 people.

Later park history
The park saw a massive increase in visitors as part of a tourism boom during the Post–World War II economic expansion. The federal government first began a program to improve roads within, and leading to, the park, at the end of the war. Later, a number of new facilities were constructed to handle the influx in visitors as part of Mission 66, a nationwide effort to improve park services by the NPS' 50th anniversary in 1966. These included a new observation tower on Clingmans Dome and the Sugarlands Visitor Center. A number of tourist attractions began to develop in Gatlinburg, Cherokee, and other nearby towns in the mid 20th century to cater to park visitors. The celebrity status of country music singer and actress Dolly Parton, who grew up in nearby Pittman Center, Tennessee, brought further attention to the park in the latter 20th and 21st centuries. In 1986, Parton cofounded the theme park Dollywood in Pigeon Forge with Herschend Family Entertainment. Dollywood resulted in a further tourist attraction boom in Gatlinburg, Pigeon Forge, and Sevierville that continues to the present day. These attractions, combined with the increasing adoption of the automobile, have brought additional visitors to the national park. This increase in tourism has greatly strained the infrastructure of the park and surrounding areas, necessitating additional road and transportation improvements.

The Great Smoky Mountains National Park was designated an International Biosphere Reserve in 1976, was certified as a UNESCO World Heritage Site in 1983, and became a part of the Southern Appalachian Biosphere Reserve in 1988. A 75th anniversary re-dedication ceremony was held on September 2, 2009. Among those in attendance were the four U.S. senators from Tennessee and North Carolina, the three U.S. Representatives whose districts include the park, the governors of both states, and Secretary of the Interior Ken Salazar. Dolly Parton also attended and performed. In 2015, Cassius Cash became the first African American superintendent of the Great Smoky Mountains National Park. He is also the 16th superintendent of the park. In late November and early December 2016, a series of wildfires engulfed a total of 17,900 acre in the park and surrounding areas. The wildfires killed at least 14, injured 190, and forced the evacuation of more than 14,000 people. The fires also damaged or destroyed at least 2,000 structures. The fires, which were initially suspected to have been caused by arson, occurred during a period of unusual drought, which accelerated the fires. The wildfires were the deadliest in the Eastern United States since the Great Fires of 1947 and comprised one of the worst natural disasters in the history of Tennessee. In 2023, the national park was featured on a USPS Priority Mail Express stamp depicting a scene near Newfound Gap. The stamp was designed by USPS art director Greg Breeding, with art from Dan Cosgrove.

title: Great Smoky Mountains National Park


text:
Presence and Instant Messaging

Presence and Instant Messaging (PRIM) was an early proposal to the IETF of a standard protocol for instant messaging.

The abstract model was first published as an IETF Request for Comments, RFC 2778 "A Model for Presence and Instant Messaging" in February 2000, which was authored by Mark Day of SightPath (formerly of Lotus Software where helped develop IBM Lotus Sametime, now Chief Scientist at Riverbed Technology), Jonathan Rosenberg of dynamicsoft (now the Chief Technology Officer and Vice President of Collaboration at Cisco Systems) and Hiroyasu Sugano of Fujitsu Laboratories LtdLtd.

No work has been done on it since 2001. Currently, SIP and its derivative SIMPLE (both of which Jonathan Rosenberg also co-authored or invented), and XMPP are being considered for use as instant messaging protocols.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Presence and Instant Messaging


text:
Nicotinamide adenine dinucleotide

Nicotinamide adenine dinucleotide (NAD) is a coenzyme central to metabolism. Found in all living cells, NAD is called a dinucleotide because it consists of two nucleotides joined through their phosphate groups. One nucleotide contains an adenine nucleobase and the other, nicotinamide. NAD exists in two forms: an oxidized and reduced form, abbreviated as NAD and NADH (H for hydrogen), respectively.

In cellular metabolism, NAD is involved in redox reactions, carrying electrons from one reaction to another, so it is found in two forms: NAD is an oxidizing agent, accepting electrons from other molecules and becoming reduced; with H+, this reaction forms NADH, which can be used as a reducing agent to donate electrons. These electron transfer reactions are the main function of NAD. It is also used in other cellular processes, most notably as a substrate of enzymes in adding or removing chemical groups to or from proteins, in posttranslational modifications. Because of the importance of these functions, the enzymes involved in NAD metabolism are targets for drug discovery.

In organisms, NAD can be synthesized from simple building-blocks (de novo) from either tryptophan or aspartic acid, each a case of an amino acid. Alternatively, more complex components of the coenzymes are taken up from nutritive compounds such as niacin; similar compounds are produced by reactions that break down the structure of NAD, providing a salvage pathway that recycles them back into their respective active form.

Some NAD is converted into the coenzyme nicotinamide adenine dinucleotide phosphate (NADP), whose chemistry largely parallels that of NAD, though its predominant role is as a coenzyme in anabolic metabolism.

In the name NAD, the superscripted plus sign indicates the positive formal charge on one of its nitrogen atoms.

Physical and chemical properties
Nicotinamide adenine dinucleotide consists of two nucleosides joined by pyrophosphate. The nucleosides each contain a ribose ring, one with adenine attached to the first carbon atom (the 1' position) (adenosine diphosphate ribose) and the other with nicotinamide at this position.

The compound accepts or donates the equivalent of H−. Such reactions (summarized in formula below) involve the removal of two hydrogen atoms from the reactant (R), in the form of a hydride ion (H−), and a proton (H). The proton is released into solution, while the reductant RH$21$ is oxidized and NAD reduced to NADH by transfer of the hydride to the nicotinamide ring.

 * RH$28$ + NAD → NADH + H + R;

From the hydride electron pair, one electron is attracted to the slightly more electronegative atom of the nicotinamide ring of NAD, becoming part of the nicotinamide moiety. The second electron and proton atom are transferred to the carbon atom adjacent to the N atom. The midpoint potential of the NAD/NADH redox pair is −0.32 volts, which makes NADH a moderately strong reducing agent. The reaction is easily reversible, when NADH reduces another molecule and is re-oxidized to NAD. This means the coenzyme can continuously cycle between the NAD and NADH forms without being consumed.

In appearance, all forms of this coenzyme are white amorphous powders that are hygroscopic and highly water-soluble. The solids are stable if stored dry and in the dark. Solutions of NAD are colorless and stable for about a week at 4 °C and neutral pH, but decompose rapidly in acidic or alkaline solutions. Upon decomposition, they form products that are enzyme inhibitors.

Both NAD and NADH strongly absorb ultraviolet light because of the adenine. For example, peak absorption of NAD is at a wavelength of 259 nanometers (nm), with an extinction coefficient of 16,900 M−1cm−1. NADH also absorbs at higher wavelengths, with a second peak in UV absorption at 339 nm with an extinction coefficient of 6,220 M−1cm−1. This difference in the ultraviolet absorption spectra between the oxidized and reduced forms of the coenzymes at higher wavelengths makes it simple to measure the conversion of one to another in enzyme assays – by measuring the amount of UV absorption at 340 nm using a spectrophotometer.

NAD and NADH also differ in their fluorescence. Freely diffusing NADH in aqueous solution, when excited at the nicotinamide absorbance of ~335 nm (near-UV), fluoresces at 445–460 nm (violet to blue) with a fluorescence lifetime of 0.4 nanoseconds, while NAD does not fluoresce. The properties of the fluorescence signal changes when NADH binds to proteins, so these changes can be used to measure dissociation constants, which are useful in the study of enzyme kinetics. These changes in fluorescence are also used to measure changes in the redox state of living cells, through fluorescence microscopy.

NADH can be converted to NAD+ in a reaction catalysed by copper, which requires hydrogen peroxide. Thus, the supply of NAD+ in cells requires mitochondrial copper(II).

Concentration and state in cells
In rat liver, the total amount of NAD and NADH is approximately 1 μmole per gram of wet weight, about 10 times the concentration of NADP and NADPH in the same cells. The actual concentration of NAD in cell cytosol is harder to measure, with recent estimates in animal cells ranging around 0.3 mM, and approximately 1.0 to 2.0 mM in yeast. However, more than 80% of NADH fluorescence in mitochondria is from bound form, so the concentration in solution is much lower.

NAD concentrations are highest in the mitochondria, constituting 40% to 70% of the total cellular NAD. NAD in the cytosol is carried into the mitochondrion by a specific membrane transport protein, since the coenzyme cannot diffuse across membranes. The intracellular half-life of NAD+ was claimed to be between 1–2 hours by one review, whereas another review gave varying estimates based on compartment: intracellular 1–4 hours, cytoplasmic 2 hours, and mitochondrial 4–6 hours.

The balance between the oxidized and reduced forms of nicotinamide adenine dinucleotide is called the NAD/NADH ratio. This ratio is an important component of what is called the redox state of a cell, a measurement that reflects both the metabolic activities and the health of cells. The effects of the NAD/NADH ratio are complex, controlling the activity of several key enzymes, including glyceraldehyde 3-phosphate dehydrogenase and pyruvate dehydrogenase. In healthy mammalian tissues, estimates of the ratio of free NAD to NADH in the cytoplasm typically lie around 700:1; the ratio is thus favorable for oxidative reactions. The ratio of total NAD/NADH is much lower, with estimates ranging from 3–10 in mammals. In contrast, the NADP/NADPH ratio is normally about 0.005, so NADPH is the dominant form of this coenzyme. These different ratios are key to the different metabolic roles of NADH and NADPH.

Biosynthesis
NAD is synthesized through two metabolic pathways. It is produced either in a de novo pathway from amino acids or in salvage pathways by recycling preformed components such as nicotinamide back to NAD. Although most tissues synthesize NAD by the salvage pathway in mammals, much more de novo synthesis occurs in the liver from tryptophan, and in the kidney and macrophages from nicotinic acid.

De novo production

Most organisms synthesize NAD from simple components. The specific set of reactions differs among organisms, but a common feature is the generation of quinolinic acid (QA) from an amino acid – either tryptophan (Trp) in animals and some bacteria, or aspartic acid (Asp) in some bacteria and plants. The quinolinic acid is converted to nicotinic acid mononucleotide (NaMN) by transfer of a phosphoribose moiety. An adenylate moiety is then transferred to form nicotinic acid adenine dinucleotide (NaAD). Finally, the nicotinic acid moiety in NaAD is amidated to a nicotinamide (Nam) moiety, forming nicotinamide adenine dinucleotide.

In a further step, some NAD is converted into NADP by NAD kinase, which phosphorylates NAD. In most organisms, this enzyme uses adenosine triphosphate (ATP) as the source of the phosphate group, although several bacteria such as Mycobacterium tuberculosis and a hyperthermophilic archaeon Pyrococcus horikoshii, use inorganic polyphosphate as an alternative phosphoryl donor.

Salvage pathways
Despite the presence of the de novo pathway, the salvage reactions are essential in humans; a lack of niacin in the diet causes the vitamin deficiency disease pellagra. This high requirement for NAD results from the constant consumption of the coenzyme in reactions such as posttranslational modifications, since the cycling of NAD between oxidized and reduced forms in redox reactions does not change the overall levels of the coenzyme. The major source of NAD in mammals is the salvage pathway which recycles the nicotinamide produced by enzymes utilizing NAD. The first step, and the rate-limiting enzyme in the salvage pathway is nicotinamide phosphoribosyltransferase (NAMPT), which produces nicotinamide mononucleotide (NMN). NMN is the immediate precursor to NAD+ in the salvage pathway.

Besides assembling NAD de novo from simple amino acid precursors, cells also salvage preformed compounds containing a pyridine base. The three vitamin precursors used in these salvage metabolic pathways are nicotinic acid (NA), nicotinamide (Nam) and nicotinamide riboside (NR). These compounds can be taken up from the diet and are termed vitamin B$7$ or niacin. However, these compounds are also produced within cells and by digestion of cellular NAD. Some of the enzymes involved in these salvage pathways appear to be concentrated in the cell nucleus, which may compensate for the high level of reactions that consume NAD in this organelle. There are some reports that mammalian cells can take up extracellular NAD from their surroundings, and both nicotinamide and nicotinamide riboside can be absorbed from the gut.

The salvage pathways used in microorganisms differ from those of mammals. Some pathogens, such as the yeast Candida glabrata and the bacterium Haemophilus influenzae are NAD auxotrophs – they cannot synthesize NAD – but possess salvage pathways and thus are dependent on external sources of NAD or its precursors. Even more surprising is the intracellular pathogen Chlamydia trachomatis, which lacks recognizable candidates for any genes involved in the biosynthesis or salvage of both NAD and NADP, and must acquire these coenzymes from its host.

Functions

Nicotinamide adenine dinucleotide has several essential roles in metabolism. It acts as a coenzyme in redox reactions, as a donor of ADP-ribose moieties in ADP-ribosylation reactions, as a precursor of the second messenger molecule cyclic ADP-ribose, as well as acting as a substrate for bacterial DNA ligases and a group of enzymes called sirtuins that use NAD to remove acetyl groups from proteins. In addition to these metabolic functions, NAD+ emerges as an adenine nucleotide that can be released from cells spontaneously and by regulated mechanisms, and can therefore have important extracellular roles.

Oxidoreductase binding of NAD
The main role of NAD in metabolism is the transfer of electrons from one molecule to another. Reactions of this type are catalyzed by a large group of enzymes called oxidoreductases. The correct names for these enzymes contain the names of both their substrates: for example NADH-ubiquinone oxidoreductase catalyzes the oxidation of NADH by coenzyme Q. However, these enzymes are also referred to as dehydrogenases or reductases, with NADH-ubiquinone oxidoreductase commonly being called NADH dehydrogenase or sometimes coenzyme Q reductase.

There are many different superfamilies of enzymes that bind NAD / NADH. One of the most common superfamilies includes a structural motif known as the Rossmann fold. The motif is named after Michael Rossmann, who was the first scientist to notice how common this structure is within nucleotide-binding proteins.

An example of a NAD-binding bacterial enzyme involved in amino acid metabolism that does not have the Rossmann fold is found in Pseudomonas syringae pv. tomato.

When bound in the active site of an oxidoreductase, the nicotinamide ring of the coenzyme is positioned so that it can accept a hydride from the other substrate. Depending on the enzyme, the hydride donor is positioned either "above" or "below" the plane of the planar C4 carbon, as defined in the figure. Class A oxidoreductases transfer the atom from above; class B enzymes transfer it from below. Since the C4 carbon that accepts the hydrogen is prochiral, this can be exploited in enzyme kinetics to give information about the enzyme's mechanism. This is done by mixing an enzyme with a substrate that has deuterium atoms substituted for the hydrogens, so the enzyme will reduce NAD by transferring deuterium rather than hydrogen. In this case, an enzyme can produce one of two stereoisomers of NADH.

Despite the similarity in how proteins bind the two coenzymes, enzymes almost always show a high level of specificity for either NAD or NADP. This specificity reflects the distinct metabolic roles of the respective coenzymes, and is the result of distinct sets of amino acid residues in the two types of coenzyme-binding pocket. For instance, in the active site of NADP-dependent enzymes, an ionic bond is formed between a basic amino acid side-chain and the acidic phosphate group of NADP. On the converse, in NAD-dependent enzymes the charge in this pocket is reversed, preventing NADP from binding. However, there are a few exceptions to this general rule, and enzymes such as aldose reductase, glucose-6-phosphate dehydrogenase, and methylenetetrahydrofolate reductase can use both coenzymes in some species.

Role in redox metabolism

The redox reactions catalyzed by oxidoreductases are vital in all parts of metabolism, but one particularly important area where these reactions occur is in the release of energy from nutrients. Here, reduced compounds such as glucose and fatty acids are oxidized, thereby releasing energy. This energy is transferred to NAD by reduction to NADH, as part of beta oxidation, glycolysis, and the citric acid cycle. In eukaryotes the electrons carried by the NADH that is produced in the cytoplasm are transferred into the mitochondrion (to reduce mitochondrial NAD) by mitochondrial shuttles, such as the malate-aspartate shuttle. The mitochondrial NADH is then oxidized in turn by the electron transport chain, which pumps protons across a membrane and generates ATP through oxidative phosphorylation. These shuttle systems also have the same transport function in chloroplasts.

Since both the oxidized and reduced forms of nicotinamide adenine dinucleotide are used in these linked sets of reactions, the cell maintains significant concentrations of both NAD and NADH, with the high NAD/NADH ratio allowing this coenzyme to act as both an oxidizing and a reducing agent. In contrast, the main function of NADPH is as a reducing agent in anabolism, with this coenzyme being involved in pathways such as fatty acid synthesis and photosynthesis. Since NADPH is needed to drive redox reactions as a strong reducing agent, the NADP/NADPH ratio is kept very low.

Although it is important in catabolism, NADH is also used in anabolic reactions, such as gluconeogenesis. This need for NADH in anabolism poses a problem for prokaryotes growing on nutrients that release only a small amount of energy. For example, nitrifying bacteria such as Nitrobacter oxidize nitrite to nitrate, which releases sufficient energy to pump protons and generate ATP, but not enough to produce NADH directly. As NADH is still needed for anabolic reactions, these bacteria use a nitrite oxidoreductase to produce enough proton-motive force to run part of the electron transport chain in reverse, generating NADH.

Non-redox roles
The coenzyme NAD is also consumed in ADP-ribose transfer reactions. For example, enzymes called ADP-ribosyltransferases add the ADP-ribose moiety of this molecule to proteins, in a posttranslational modification called ADP-ribosylation. ADP-ribosylation involves either the addition of a single ADP-ribose moiety, in mono-ADP-ribosylation, or the transferral of ADP-ribose to proteins in long branched chains, which is called poly(ADP-ribosyl)ation. Mono-ADP-ribosylation was first identified as the mechanism of a group of bacterial toxins, notably cholera toxin, but it is also involved in normal cell signaling. Poly(ADP-ribosyl)ation is carried out by the poly(ADP-ribose) polymerases. The poly(ADP-ribose) structure is involved in the regulation of several cellular events and is most important in the cell nucleus, in processes such as DNA repair and telomere maintenance. In addition to these functions within the cell, a group of extracellular ADP-ribosyltransferases has recently been discovered, but their functions remain obscure. NAD may also be added onto cellular RNA as a 5'-terminal modification.

Another function of this coenzyme in cell signaling is as a precursor of cyclic ADP-ribose, which is produced from NAD by ADP-ribosyl cyclases, as part of a second messenger system. This molecule acts in calcium signaling by releasing calcium from intracellular stores. It does this by binding to and opening a class of calcium channels called ryanodine receptors, which are located in the membranes of organelles, such as the endoplasmic reticulum, and inducing the activation of the transcription factor NAFC3

NAD is also consumed by different NAD+-consuming enzymes, such as CD38, CD157, PARPs and the NAD-dependent deacetylases (sirtuins,such as Sir2. ). These enzymes act by transferring an acetyl group from their substrate protein to the ADP-ribose moiety of NAD; this cleaves the coenzyme and releases nicotinamide and O-acetyl-ADP-ribose. The sirtuins mainly seem to be involved in regulating transcription through deacetylating histones and altering nucleosome structure. However, non-histone proteins can be deacetylated by sirtuins as well. These activities of sirtuins are particularly interesting because of their importance in the regulation of aging.

Other NAD-dependent enzymes include bacterial DNA ligases, which join two DNA ends by using NAD as a substrate to donate an adenosine monophosphate (AMP) moiety to the 5' phosphate of one DNA end. This intermediate is then attacked by the 3' hydroxyl group of the other DNA end, forming a new phosphodiester bond. This contrasts with eukaryotic DNA ligases, which use ATP to form the DNA-AMP intermediate.

Li et al. have found that NAD directly regulates protein-protein interactions. They also show that one of the causes of age-related decline in DNA repair may be increased binding of the protein DBC1 (Deleted in Breast Cancer 1) to PARP1 (poly[ADP–ribose] polymerase 1) as NAD levels decline during aging. The decline in cellular concentrations of NAD during aging likely contributes to the aging process and to the pathogenesis of the chronic diseases of aging. Thus, the modulation of NAD may protect against cancer, radiation, and aging.

Extracellular actions of NAD+
In recent years, NAD+ has also been recognized as an extracellular signaling molecule involved in cell-to-cell communication. NAD+ is released from neurons in blood vessels, urinary bladder, large intestine, from neurosecretory cells, and from brain synaptosomes, and is proposed to be a novel neurotransmitter that transmits information from nerves to effector cells in smooth muscle organs. In plants, the extracellular nicotinamide adenine dinucleotide induces resistance to pathogen infection and the first extracellular NAD receptor has been identified. Further studies are needed to determine the underlying mechanisms of its extracellular actions and their importance for human health and life processes in other organisms.

Clinical significance
The enzymes that make and use NAD and NADH are important in both pharmacology and the research into future treatments for disease. Drug design and drug development exploits NAD in three ways: as a direct target of drugs, by designing enzyme inhibitors or activators based on its structure that change the activity of NAD-dependent enzymes, and by trying to inhibit NAD biosynthesis.

Because cancer cells utilize increased glycolysis, and because NAD enhances glycolysis, nicotinamide phosphoribosyltransferase (NAD salvage pathway) is often amplified in cancer cells.

It has been studied for its potential use in the therapy of neurodegenerative diseases such as Alzheimer's and Parkinson's disease as well as multiple sclerosis. A placebo-controlled clinical trial of NADH (which excluded NADH precursors) in people with Parkinson's failed to show any effect.

NAD is also a direct target of the drug isoniazid, which is used in the treatment of tuberculosis, an infection caused by Mycobacterium tuberculosis. Isoniazid is a prodrug and once it has entered the bacteria, it is activated by a peroxidase enzyme, which oxidizes the compound into a free radical form. This radical then reacts with NADH, to produce adducts that are very potent inhibitors of the enzymes enoyl-acyl carrier protein reductase, and dihydrofolate reductase.

Since many oxidoreductases use NAD and NADH as substrates, and bind them using a highly conserved structural motif, the idea that inhibitors based on NAD could be specific to one enzyme is surprising. However, this can be possible: for example, inhibitors based on the compounds mycophenolic acid and tiazofurin inhibit IMP dehydrogenase at the NAD binding site. Because of the importance of this enzyme in purine metabolism, these compounds may be useful as anti-cancer, anti-viral, or immunosuppressive drugs. Other drugs are not enzyme inhibitors, but instead activate enzymes involved in NAD metabolism. Sirtuins are a particularly interesting target for such drugs, since activation of these NAD-dependent deacetylases extends lifespan in some animal models. Compounds such as resveratrol increase the activity of these enzymes, which may be important in their ability to delay aging in both vertebrate, and invertebrate model organisms. In one experiment, mice given NAD for one week had improved nuclear-mitochrondrial communication.

Because of the differences in the metabolic pathways of NAD biosynthesis between organisms, such as between bacteria and humans, this area of metabolism is a promising area for the development of new antibiotics. For example, the enzyme nicotinamidase, which converts nicotinamide to nicotinic acid, is a target for drug design, as this enzyme is absent in humans but present in yeast and bacteria.

In bacteriology, NAD, sometimes referred to factor V, is used as a supplement to culture media for some fastidious bacteria.

History

The coenzyme NAD was first discovered by the British biochemists Arthur Harden and William John Young in 1906. They noticed that adding boiled and filtered yeast extract greatly accelerated alcoholic fermentation in unboiled yeast extracts. They called the unidentified factor responsible for this effect a coferment. Through a long and difficult purification from yeast extracts, this heat-stable factor was identified as a nucleotide sugar phosphate by Hans von Euler-Chelpin. In 1936, the German scientist Otto Heinrich Warburg showed the function of the nucleotide coenzyme in hydride transfer and identified the nicotinamide portion as the site of redox reactions.

Vitamin precursors of NAD were first identified in 1938, when Conrad Elvehjem showed that liver has an "anti-black tongue" activity in the form of nicotinamide. Then, in 1939, he provided the first strong evidence that niacin is used to synthesize NAD. In the early 1940s, Arthur Kornberg was the first to detect an enzyme in the biosynthetic pathway. In 1949, the American biochemists Morris Friedkin and Albert L. Lehninger proved that NADH linked metabolic pathways such as the citric acid cycle with the synthesis of ATP in oxidative phosphorylation. In 1958, Jack Preiss and Philip Handler discovered the intermediates and enzymes involved in the biosynthesis of NAD; salvage synthesis from nicotinic acid is termed the Preiss-Handler pathway. In 2004, Charles Brenner and co-workers uncovered the nicotinamide riboside kinase pathway to NAD.

The non-redox roles of NAD(P) were discovered later. The first to be identified was the use of NAD as the ADP-ribose donor in ADP-ribosylation reactions, observed in the early 1960s. Studies in the 1980s and 1990s revealed the activities of NAD and NADP metabolites in cell signaling – such as the action of cyclic ADP-ribose, which was discovered in 1987.

The metabolism of NAD remained an area of intense research into the 21st century, with interest heightened after the discovery of the NAD-dependent protein deacetylases called sirtuins in 2000, by Shin-ichiro Imai and coworkers in the laboratory of Leonard P. Guarente. In 2009 Imai proposed the "NAD World" hypothesis that key regulators of aging and longevity in mammals are sirtuin 1 and the primary NAD synthesizing enzyme nicotinamide phosphoribosyltransferase (NAMPT). In 2016 Imai expanded his hypothesis to "NAD World 2.0", which postulates that extracellular NAMPT from adipose tissue maintains NAD in the hypothalamus (the control center) in conjunction with myokines from skeletal muscle cells. In 2018, Napa Therapeutics was formed to develop drugs against a novel aging related target based on the research in NAD metabolism conducted in the lab of Eric Verdin.

History

 * , A history of early enzymology.
 * , a textbook from the 19th century.

title: Nicotinamide adenine dinucleotide


text:
Society of Antiquaries of Scotland

The Society of Antiquaries of Scotland is the senior antiquarian body of Scotland, with its headquarters in the National Museum of Scotland, Chambers Street, Edinburgh. The Society's aim is to promote the cultural heritage of Scotland.

The usual style of post-nominal letters for fellows is FSAScot.

History
The Society is the oldest antiquarian society in Scotland, and the second-oldest in Britain after the Society of Antiquaries of London. Founded by David Erskine, 11th Earl of Buchan on 18 December 1780, John Stuart, 3rd Earl of Bute, the former prime minister, was elected the first President. It was incorporated by Royal Charter in 1783, in the same year as the Royal Society of Edinburgh, and in their early years both societies shared accommodation on George Street and in the Royal Institution building on The Mound. Members of the Society collected artefacts of interest to Scottish history and culture from its foundation, and soon the Society developed a sizeable collection. In November 1851 the signing of a Deed of Conveyance with the Board of Manufactures on behalf of Parliament made the Society collections National Property. In 1891 the antiquaries moved into the purpose-built Scottish National Portrait Gallery and National Museum of Antiquities of Scotland, located on Queen Street. The National Museum of Antiquities of Scotland Act 1954 transferred the powers and duties relating to the Museum, previously vested in the Society of Antiquaries and the National Galleries, to a new Board. The Society is now an independent not-for-profit charity registered in Scotland (SC010440).

Alexander Rhind left a bequest to the Society to fund a lecture series, the Rhind Lectures are still hosted by the Society; an online recording of these prestigious lectures has been made available to the public since 2009.

Objects
The Society of Antiquaries of Scotland is a charitable organisation whose purpose is set out in its Royal Charter from 1783:

"…a Society to investigate both antiquities and natural and civil history in general, with the intention that the talents of mankind should be cultivated and that the study of natural and useful sciences should be promoted."

The first Law of the Society focuses this further: "The purpose of the Society shall be the study of the Antiquities and History of Scotland, more especially by means of Archaeological Research."

The Society today is concerned with every aspect of the human past in Scotland. It draws on a wide range of experience through the Fellowship, and provides a voice for Scotland's heritage independent of the opinions of Government, University, or Agency. The Society is consulted by a wide range of organisations from central government to academic funding bodies such as the Arts & Humanities Research Council. The Society makes written responses to numerous consultations, some jointly with Archaeology Scotland (formerly CSA) and the Scottish Group of the Chartered Institute for Archaeologists. The Society worked closely with the Historic Environment Advisory Council for Scotland (HEACS was abolished by the Public Services Reform (Scotland) Act 2010 as part of the Scottish Government's policy to simplify the landscape of public bodies), and gave evidence to their working groups on heritage protection legislation and properties in care. The Society has also been actively involved in the Built Environment Forum Scotland, an umbrella body for NGOs in the built and historic environment sectors.

Fellowship
Members of the Society have, since 1823, been known as Fellows of the Society. There are now thousands of Fellows spread across the globe, including Honorary Fellows elected for their outstanding scholarship. Fellowship recognises a person's support and contributions to the purpose and mission of the Society, and Fellows are permitted to use the post-nominals FSAScot (NB Not FSA (Scot) or similar). The Society has an international membership of around 2800 Fellows and a maximum of 25 Honorary Fellows. Admission to the Society is by election, and candidates must be supported by existing Fellows. The names of those seeking admission are then circulated to the whole Fellowship. Elections are held biannually at the Anniversary Meeting (AGM) on St Andrew's Day, 30 November, and in Spring, usually in April. Fundamental to being a candidate for election to the Fellowship is an interest or involvement in Scotland's past. Candidates are advised of the outcome of the election shortly after the ballot.

Supporting research
A major part of the Society's programme is support for research into Scotland's past, and there are various grants and awards to assist different kinds of work, from survey and excavation to finds analysis and archival research.

Other prizes and awards
The Society also encourages best practice and continued research into Scotland's past through various prizes and awards.

 * The RBK Stevenson Award - This award is offered annually in recognition of the article published in the Proceedings on a topic that best reflects the scholarship and high standards of this distinguished individual, who was for many years the Keeper of the National Museum of Antiquities of Scotland and was President of the Society between 1975 and 1978.
 * The Dorothy Marshall Medal - Awarded every three years by the Council of the Society for an outstanding contribution, in a voluntary capacity, to Scottish archaeological or related work.
 * The Murray Prize for History - Awarded biennially to recognise original research published by the Society into the history of Scotland in the medieval and/or early modern periods (c AD 500 to AD 1700).
 * Chalmers-Jervise Prize - Awarded biennially for the best paper published by the Society to cover any subject in the prehistory or archaeology of Scotland before AD 1100.

Lectures and events
The Society hosts monthly lectures, usually between October and May, and generally held in Edinburgh, although some are jointly hosted with other Societies elsewhere in Scotland. The Society can also fund other local Societies to invite a lecturer to them; this lecture is called the Buchan Lecture.

In addition, the Society hosts the prestigious Rhind Lectures, a series of six lectures, often presented by a single lecturer over a weekend. These allow the lecturer to present their topic in much greater detail and depth than otherwise possible, and are often published. The Rhind lectures began in 1874 after the death of Alexander Rhind who left the residue of his estate to endow a lectureship in the Society and there have now been over 130 lectures and many have become the published textbook for a generation.

 * Society lectures and other events are now recorded where possible and placed online on the Society website free to view.
 * The Rhind Lectures are similarly recorded and available to view since 2009.

Publications
The Society of Antiquaries of Scotland has three main publishing outputs:

 * Peer-reviewed Books, previously known as monographs, covering a wide variety of topics in the history and archaeology of Scotland.
 * The Proceedings of the Society of Antiquaries of Scotland, a yearly peer-reviewed journal covering the latest archaeological and historical research in Scotland. The Society has made the entire run of the Proceedings since 1851, and its predecessor Archaeologica Scotica back to 1792, freely available on the internet.
 * Scottish Archaeological Internet Reports (SAIR, ) is a peer-reviewed online publication that includes larger and more data-rich projects. It is freely accessible without subscription or payment.

There is also a regular Society Newsletter, and the Society publishes book reviews on their website.

List of presidents
The following have served as presidents of the Society:

 * John Stuart, 3rd Earl of Bute (1780–1792)
 * James Graham, 4th Duke of Montrose (1792–1813)
 * Lawrence Dundas, 1st Earl of Zetland (1813–1819)
 * Francis Gray, 14th Lord Gray (1819–1923)
 * Thomas Bruce, 7th Earl of Elgin and 11th Earl of Kincardine (1823–1841)
 * James Bruce, 8th Earl of Elgin (1841–1844)
 * Walter Montagu Douglas Scott, 5th Duke of Buccleuch (1844–1862)
 * George Granville William Sutherland-Leveson-Gower, 3rd Duke of Sutherland (1872–1876)
 * Schomberg Henry Kerr, 9th Marquess of Lothian (1876–1900)
 * Sir Herbert Maxwell, 7th Baronet (1900–1913)
 * John Abercromby, 5th Baron Abercromby (1913–1918)
 * Thomas Gibson-Carmichael, 1st Baron Carmichael (1918–1923)
 * John Stewart-Murray, 8th Duke of Atholl (1923–1933)
 * George Macdonald (archaeologist) (1933–1940)
 * Sir John Stirling-Maxwell, 10th Baronet (1940–1945)
 * George Baillie-Hamilton, 12th Earl of Haddington (1945–1950)
 * William Moir Calder (1950–1955)
 * James Latham Clyde, Lord Clyde (1955–1960)
 * James Frederick Gordon Thomson, the Hon Lord Migdale (1960–1965)
 * James Scott-Elliot (1965–1967)
 * Stuart Piggott (1967–1972)
 * Kenneth Arthur Steer (1972–1975)
 * Robert Barron Kerr Stevenson (1975–1978)
 * Ronald Gordon Cant (1978–1981)
 * Stuart Maxwell (1981–1984)
 * Leslie Alcock (1984–1987)
 * David Breeze (1987–1990)
 * Anna Ritchie (1990–1993)
 * Gordon Stirling Maxwell (1993–1996)
 * Michael Lynch (1996–1999)
 * James Neil Graham Ritchie (1999–2002)
 * Lisbeth Margaret Thoms (2002–2005)
 * Roger Mercer (2005–2008)
 * Barbara E. Crawford (2008–2011)
 * Alan Saville (2011–2014)
 * David Hepburn Caldwell (2014–2020)
 * Ian Ralston (2020–2023)
 * Diana Murray (2023–Present)

Notable vice presidents

 * David Erskine, 11th Earl of Buchan, founder of the Society in 1780 and first vice president (1780–1792)
 * Sir Walter Scott (1827–1829)
 * Sir James Young Simpson (1860–1870)
 * John Alexander Smith (1870–1873)

title: Society of Antiquaries of Scotland