text:
List of rivers of Pennsylvania

This is a list of streams and rivers in the U.S. state of Pennsylvania.

By drainage basin
This list is arranged by drainage basin, with respective tributaries indented under each larger stream's name.

Delaware Bay
• Delaware River

• *Christina River

• **Brandywine Creek

• ***Pocopson Creek

• ***East Branch Brandywine Creek

• ****Valley Creek

• ***West Branch Brandywine Creek

• ****Broad Run

• ****Buck Run

• *****Doe Run

• **White Clay Creek

• ***Red Clay Creek

• ****Burrows Run

• ***Mill Creek

• ***Broad Run

• ***Bogy Run

• ***Middle Run

• ***Walnut Run

• *Naamans Creek

• *Marcus Hook Creek

• *Stoney Creek

• *Chester Creek

• **Baldwin Run

• **Rocky Run

• **Goose Creek

• **East Branch Chester Creek

• **West Branch Chester Creek

• ***Webb Creek

• *Ridley Creek

• **Vernon Run

• **Spring Run

• **Dismal Run

• **Hunters Run

• *Crum Creek

• **Little Crum Creek

• **Stony Creek

• **Trout Run

• **West Crum Creek

• *Darby Creek

• **Stoney Creek

• **Muckinipattis Creek

• **Hermesprota Creek

• **Bow Creek (Tidal stream, flowed into what once was the back channel of Hog Island. Obliterated due to the expansion of I 95.)

• **Cobbs Creek

• ***Naylors Run

• ***Indian Creek

• **Ithan Creek

• ***Meadowbrook Run

• **Little Darby Creek

• *Schuylkill River

• **Shed Brook (In Franklin Delano Roosevelt Park.)

• **Mingo Creek (Tidal stream, formerly flowed into Eastwick, Philadelphia. Now converted to a surge basin.)

• **Mill Creek (Philadelphia)

• **Wissahickon Creek

• ***Paper Mill Run

• ***Cresheim Creek

• ***Sandy Run

• **Mill Creek (Montgomery County, Pennsylvania)

• **Plymouth Creek

• **Gulph Creek

• **Stony Creek

• **Valley Creek

• **Trout Creek

• **Perkiomen Creek

• ***Skippack Creek

• ****Towamencin Creek

• ***East Branch Perkiomen Creek

• ****Pleasant Spring Creek

• ***Swamp Creek

• ****Scioto Creek

• ***Unami Creek

• ****Ridge Valley Creek

• ***Macoby Creek

• ***West Branch Perkiomen Creek

• ***Hosensack Creek

• **Pickering Creek

• **French Creek

• ***Scotts Run

• **Mingo Creek (Montgomery County, Pennsylvania)

• **Pigeon Creek

• **Manatawny Creek

• ***Ironstone Creek

• ***Little Manatawny Creek

• ***Bieber Creek

• ***Pine Creek

• **Monocacy Creek

• **Hay Creek

• **Antietam Creek

• **Allegheny Creek

• **Angelica Creek

• **Wyomissing Creek

• **Tulpehocken Creek

• ***Cacoosing Creek

• ***Plum Creek

• ***Northkill Creek

• ****Little Northkill Creek

• ****Wolf Creek

• ***Spring Creek

• ***Mill Creek

• **Maiden Creek

• ***Willow Creek

• ***Moselem Creek

• ***Sacony Creek

• ****Mill Creek

• ***Stony Run

• ***Kistler Creek

• ***Ontelaunee Creek

• **Irish Creek

• **Mill Creek

• **Little Schuylkill River

• ***Indian Run

• ***Panther Creek

• ***Locust Creek

• ***Pine Creek

• **Pine Creek

• **West Branch Schuylkill River

• ***West West Branch Schuylkill River

• ****West Creek

• **Norwegian Creek

• **Mill Creek (Port Carbon, Pennsylvania)

• **Silver Creek

• *Hollander's Creek (in Franklin Delano Roosevelt Park)

• *Dock Creek

• *Cohoquinoque Creek

• *Cohocksink Creek

• *Gunner's Run (obliterated to sewer)

• *Frankford Creek

• **Little Tacony Creek (obliterated to sewer)

• **Tacony Creek

• **Wingohocking Creek

• *Wissinoming Creek (obliterated to sewer)

• *Pennypack Creek

• *Poquessing Creek

• **Byberry Creek

• **Bloody Run

• *Neshaminy Creek

• **Mill Creek

• ***Pine Run

• ***Ironworks Creek

• **Newtown Creek

• **Mill Creek

• ***Robin Run

• ***Watson Creek

• ***Lahaska Creek

• **Little Neshaminy Creek

• ***Park Creek

• **Cooks Run

• **Mill Creek

• **North Branch Neshaminy Creek

• ***Pine Run

• **West Branch Neshaminy Creek

• ***Reading Creek

• *Mill Creek

• **Queen Anne Creek

• **Black Ditch Creek

• **Adams Hollow Creek

• *Martins Creek

• *Scotts Creek

• *Biles Creek

• *Buck Creek

• **Brock Creek

• *Dyers Creek

• *Houghs Creek

• *Jericho Creek

• *Pidcock Creek

• **Curls Run

• *Dark Hollow Run

• *Aquetong Creek

• *Rabbit Run

• *Cuttalosa Creek

• *Paunnacussing Creek

• *Hickory Creek

• *Tohickon Creek

• **Geddes Run

• **Cabin Run

• **Deep Run

• **Wolf Run

• **Deer Run

• **Mink Run

• **Haycock Creek

• **Threemile Run

• **Dimple Creek

• **Dry Branch Creek

• **Morgan Creek

• **Beaver Run

• ***Licking Run

• *Smithtown Creek

• *Tinicum Creek

• **Beaver Creek

• **Rapp Creek

• *Swamp Creek

• *Falls Creek

• *Gallows Run

• *Rodges Run

• *Cooks Creek

• **Hollow Run

• *Lehigh River

• **Saucon Creek

• ***East Branch Saucon Creek

• ***Laurel Run

• **Monocacy Creek

• ***East Branch Monocacy Creek

• **Little Lehigh Creek

• ***Jordan Creek

• ***Cedar Creek

• ***Spring Creek

• ***Swabia Creek

• **Catasauqua Creek

• **Coplay Creek

• **Hokendauqua Creek

• ***Indian Creek

• **Trout Creek

• **Aquashicola Creek

• ***Buckwha Creek

• **Lizard Creek

• **Pohopoco Creek

• **Mahoning Creek

• **Mauch Chunk Creek / White Bear Creek

• **Nesquehoning Creek

• ***Jeans Run

• **Black Creek

• ***Quakake Creek

• ***Beaver Creek

• ***Hazle Creek

• **Mud Run

• **Bear Creek

• **Tobyhanna Creek

• ***Tunkhannock Creek

• ****South Branch Tunkhannock Creek

• *Bushkill Creek

• **Little Bushkill Creek

• *Martins Creek

• *Cherry Creek

• *Brodhead Creek

• **Marshalls Creek

• **McMichael Creek

• ***Pocono Creek

• ***Appenzell Creek

• **Paradise Creek

• ***Swiftwater Creek

• **Stony Run

• **Buck Hill Creek

• **Leavitt Branch

• **Middle Branch Brodhead Creek

• *Big Bushkill Creek

• **Little Bush Kill

• **Saw Creek

• **Rock Hill Creek

• *Raymondskill Creek

• **Dwarf Kill

• *Dingmans Creek

• *Sawkill Creek

• *Shohola Creek

• *Lackawaxen River

• **Blooming Grove Creek

• **Wallenpaupack Creek

• ***West Branch Wallenpaupack Creek

• ***East Branch Wallenpaupack Creek

• ****Bridge Creek

• **Middle Creek

• **Carley Brook

• **Dyberry Creek

• ***West Branch Dyberry Creek

• **Van Auken Creek

• **West Branch Lackawaxen River

• ***Johnson Creek

• *Calkins Creek

• *Equinunk Creek

• *West Branch Delaware River

• **Shehawken Creek

Chesapeake Bay

 * Elk River (MD)
 * Big Elk Creek
 * Little Elk Creek
 * North East River (MD)
 * North East Creek
 * Gunpowder River

Susquehanna River

 * Susquehanna River
 * Deer Creek
 * Octoraro Creek
 * West Branch Octoraro Creek
 * Stewart Run
 * East Branch Octoraro Creek
 * Muddy Run
 * Conowingo Creek
 * Fishing Creek (Lancaster County)
 * Muddy Creek (Susquehanna River tributary)
 * North Branch Muddy Creek
 * South Branch Muddy Creek
 * Tucquan Creek
 * Otter Creek
 * Pequea Creek
 * Big Beaver Creek
 * Little Beaver Creek
 * Conestoga River
 * Little Conestoga Creek
 * Mill Creek
 * Lititz Run
 * Cocalico Creek
 * Hammer Creek
 * Middle Creek
 * Indian Run
 * Little Cocalico Creek
 * Muddy Creek (Conestoga River tributary)
 * Little Muddy Creek
 * Fishing Creek (York County)
 * Cabin Creek
 * Kreutz Creek
 * Chiques Creek (known as Chickies Creek until 2002)
 * Donegal Creek
 * Little Chiques Creek
 * Codorus Creek
 * South Branch Codorus Creek
 * East Branch Codorus Creek
 * Centerville Creek
 * West Branch Codorus Creek
 * Oil Creek
 * Conoy Creek
 * Black Gut
 * Conewago Creek (west) (in Adams and York counties)
 * Little Conewago Creek (west)
 * Bennett Run
 * Beaver Creek (York County)
 * Beaver Creek (Adams County)
 * Bermudian Creek
 * Mud Run
 * North Branch Bermudian Creek
 * Latimore Creek
 * South Branch Conewago Creek
 * Opossum Creek
 * Conewago Creek (east) (in Lebanon, Dauphin, and Lancaster counties)
 * Lynch Run
 * Brills Run
 * Hoffer Creek
 * Little Conewago Creek (east)
 * Fishing Creek (Newberry Township)
 * Swatara Creek
 * Iron Run
 * Beaver Creek
 * Spring Creek
 * Manada Creek
 * Bow Creek
 * Quittapahilla Creek
 * Snitz Creek
 * Brandywine Creek (Quittapahilla Creek tributary)
 * Indiantown Run
 * Little Swatara Creek
 * Elizabeth Run
 * Crosskill Creek
 * Mill Creek
 * Lower Little Swatara Creek
 * Upper Little Swatara Creek
 * Good Spring Creek
 * Yellow Breeches Creek
 * Stony Run
 * Mountain Creek
 * Spring Creek
 * Slotznick Run
 * Paxton Creek
 * Asylum Run
 * Black Run
 * Conodoguinet Creek
 * Hogestown Run
 * LeTort Spring Run
 * Big Spring Creek
 * Doubling Gap Creek
 * Middle Spring Creek
 * Muddy Run (Conodoguinet Creek tributary)
 * Rowe Run
 * Lehman Run
 * Trout Run (Conodoguinet Creek tributary)
 * Fishing Creek (east bank Susquehanna River tributary)
 * Fishing Creek (Perry County) (west bank Susquehanna River tributary)
 * Stony Creek
 * Rattling Run
 * Rausch Creek
 * Clark Creek
 * Shermans Creek
 * Laurel Run
 * Bixler's Run
 * Little Juniata Creek
 * Juniata River
 * Little Buffalo Creek
 * Buffalo Creek
 * Wildcat Run
 * Cocolamus Creek
 * Delaware Creek
 * Raccoon Creek
 * Doe Run
 * Tuscarora Creek
 * East Licking Creek
 * Dougherty Run
 * Narrows Branch Tuscarora Creek
 * Lost Creek
 * Jacks Creek
 * Kishacoquillas Creek
 * Tea Creek
 * Honey Creek
 * Laurel Creek
 * Treaster Run
 * Havice Creek
 * Little Kishacoquillas Creek
 * West Licking Creek
 * Aughwick Creek
 * Blacklog Creek
 * Shade Creek
 * Three Springs Creek
 * Little Aughwick Creek
 * North Branch Little Aughwick Creek
 * South Branch Little Aughwick Creek
 * Sideling Hill Creek
 * Wooden Bridge Creek
 * Roaring Run
 * Mill Creek
 * Saddler Creek
 * Raystown Branch Juniata River
 * Great Trough Creek
 * Little Trough Creek
 * Shoup Run
 * Yellow Creek
 * Brush Creek (Raystown Branch Juniata River tributary)
 * Shaffer Creek
 * Brush Creek (Shaffer Creek tributary)
 * Chapman Run
 * Clear Creek
 * Bloody Run
 * Cove Creek
 * Dunning Creek
 * Bobs Creek
 * Shobers Run
 * Buffalo Run
 * Milligan Run
 * Shawnee Branch
 * Standing Stone Creek
 * East Branch Standing Stone Creek
 * Laurel Run
 * Crooked Creek
 * Shaver Creek
 * Little Juniata River
 * Spruce Creek
 * Warriors Mark Run
 * Sinking Run
 * Bald Eagle Creek
 * Bells Gap Run
 * Frankstown Branch Juniata River
 * Clover Creek
 * Snare Run
 * Piney Creek
 * Canoe Creek
 * Beaverdam Branch Juniata River
 * Brush Run
 * Blair Gap Run
 * Sugar Run
 * Burgoon Run
 * Mill Run
 * Halter Creek
 * Powell Creek
 * Armstrong Creek
 * Hunters Run
 * Wiconisco Creek
 * Little Wiconisco Creek
 * Rattling Creek
 * Shippens Run
 * Bargers Run
 * Barger Run
 * Toad Hollow
 * Spruce Run
 * Mahantango Creek
 * Deep Creek
 * Snow Creek
 * Pine Creek
 * Deep Creek
 * Hans Yost Creek
 * Rausch Creek
 * East Branch Rausch Creek
 * West Branch Rausch Creek
 * Little Mahantango Creek
 * Boyers Run
 * Mahantango Creek
 * North Branch Mahantango Creek
 * Aline Creek
 * West Branch Mahantango Creek
 * Dobson Run
 * Leiningers Run
 * Quaker Run
 * Hoffer Creek
 * Dalmatia Creek
 * Independence Run
 * Chapman Creek
 * Herrold Run
 * Silver Creek
 * Fidlers Run
 * Mahanoy Creek
 * Schwaben Creek
 * Mouse Creek
 * Middle Creek
 * Zerbe Run
 * Crab Run
 * Little Mahanoy Creek
 * Rattling Run
 * Shenandoah Creek
 * Lost Creek
 * Kehly Run
 * North Mahanoy Creek
 * Penns Creek
 * Middle Creek
 * Susquehecka Creek
 * Dry Run
 * Kern Run
 * Wetzel Run
 * Luphers Run
 * Beaver Creek
 * Pine Creek
 * Elk Creek
 * Sinking Creek
 * Potter Run
 * Boile Run
 * Hallowing Run
 * Sealholtz Run
 * Rolling Green Run
 * Shamokin Creek
 * Little Shamokin Creek
 * Plum Creek
 * Lick Creek
 * Millers Run
 * Bennys Run
 * Trout Run
 * Furnace Run
 * Carbon Run
 * Coal Run
 * Quaker Run
 * Locust Creek
 * North Branch Shamokin Creek
 * West Branch Susquehanna River
 * Winfield Creek
 * Turtle Creek
 * Chillisquaque Creek
 * Beaver Run
 * Mud Creek (Chillisquaque Creek tributary)
 * West Branch Chillisquaque Creek
 * County Line Branch
 * McKee Run
 * Beaver Run
 * East Branch Chillisquaque Creek
 * White Hall Creek
 * Middle Branch Chillisquaque Creek
 * Buffalo Creek
 * Little Buffalo Creek
 * Spruce Run
 * Muddy Run
 * Black Run
 * Beaver Run
 * Stony Run
 * Rapid Run
 * Halfway Run
 * Yankee Run
 * North Branch Buffalo Creek
 * Coal Run
 * Panther Run
 * Slide Hollow
 * Limestone Run (Montour and Northumberland Counties, Pennsylvania)
 * Muddy Run
 * Warrior Run
 * White Deer Creek
 * Lick Run
 * Mile Run
 * Sand Spring Run
 * Cowbell Hollow
 * Tunis Run
 * Spring Run
 * Dry Run
 * Delaware Run
 * White Deer Hole Creek
 * Spring Creek
 * Beartrap Hollow
 * Black Run
 * Black Hole Creek
 * Turkey Run
 * Glade Run
 * Muncy Creek
 * Wolf Run
 * Oak Run
 * Little Muncy Creek
 * Cox Run
 * Shepman Run
 * Laurel Run
 * Broad Run
 * German Run
 * Jakes Run
 * Derr Run
 * Big Run
 * Beaver Run
 * Marsh Run
 * Little Indian Run
 * West Branch Little Muncy Creek
 * West Creek
 * Buck Run
 * Loyalsock Creek
 * Mill Creek
 * Wallis Run
 * Bear Creek
 * Plunketts Creek
 * Elk Creek
 * Hoagland Branch
 * Kings Creek
 * Little Loyalsock Creek
 * Black Creek
 * Birch Creek
 * Lopez Creek
 * Pigeon Creek
 * Lycoming Creek
 * Pleasant Stream
 * Rock Run
 * Roaring Branch
 * Larrys Creek
 * Rauchtown Run/Antes Creek
 * Pine Creek
 * Little Pine Creek
 * Texas Creek
 * Hughes Run
 * Zimmerman Creek
 * Blockhouse Creek
 * Blacks Creek
 * Slate Run
 * Cedar Run
 * Babb Creek
 * Stony Fork Creek
 * Marsh Creek
 * West Branch Pine Creek
 * Lyman Run
 * Genesee Forks
 * Bald Eagle Creek
 * Fishing Creek
 * Little Fishing Creek
 * Beech Creek
 * Marsh Creek
 * Spring Creek
 * Buffalo Run
 * Logan Branch
 * Slab Cabin Run
 * Spring Creek
 * Wallace Run
 * Lick Run
 * Tangascootack Creek
 * North Fork Tangascootack Creek
 * Hyner Run
 * Young Womans Creek
 * Drury Run
 * Kettle Creek
 * Twomile Run
 * Middle Branch Twomile Run
 * Huling Branch
 * Hammersley Fork
 * Little Kettle Creek
 * Cross Fork
 * Fish Dam Run
 * Dennison Fork
 * Cooks Run
 * Lick Run
 * Sinnemahoning Creek
 * First Fork Sinnemahoning Creek
 * Bailey Run
 * East Fork Sinnemahoning Creek
 * Freeman Run
 * Bennett Branch
 * Trout Run
 * Medix Run
 * Laurel Run
 * Driftwood Branch
 * Sinnemahoning Portage Creek
 * West Creek
 * North Creek
 * Clear Creek
 * Birch Island Run
 * Mosquito Creek
 * Gifford Run
 * Moshannon Creek
 * Black Moshannon Creek
 * Cold Stream
 * Deer Creek
 * Trout Run
 * Lick Run
 * Flegals Run
 * Jerrys Run
 * Fork Run
 * Stone Run
 * Clearfield Creek
 * Little Clearfield Creek
 * Gazzam Run
 * Watts Creek
 * Anderson Creek
 * Kratzer Run
 * Bilger Run
 * Fenton Run
 * Hughey Run
 * Bear Run
 * Little Anderson Creek
 * Panther Run
 * Irvin Branch
 * Montgomery Run
 * Burns Run
 * Coupler Run
 * Dressler Run
 * Blanchard Run
 * Stony Run
 * Whitney Run
 * Chest Creek
 * Bear Run
 * Cush Creek
 * Lithia Springs Creek
 * Johnson Creek
 * Gravel Run
 * Packers Run
 * Raups Run
 * Kipps Run
 * Wilson Run
 * Gaskins Run
 * Mahoning Creek (Susquehanna River tributary)
 * Sechler Run
 * Blizzards Run
 * Kase Run
 * Mauses Creek
 * Indian Creek
 * Toby Run
 * Logan Run
 * Little Roaring Creek
 * Roaring Creek
 * South Branch Roaring Creek
 * Mugser Run
 * Lick Run
 * Mill Creek
 * Catawissa Creek
 * Furnace Run
 * Scotch Run
 * Fisher Run
 * Mine Gap Run
 * Beaver Run
 * Long Hollow
 * Stranger Hollow
 * Klingermans Run
 * Cranberry Run
 * Crooked Run
 * Tomhicken Creek
 * Raccoon Creek
 * Little Crooked Run
 * Sugarloaf Creek
 * Little Tomhicken Creek
 * Little Catawissa Creek
 * Stony Run
 * Trexler Run
 * Dark Run
 * Rattling Run
 * Davis Run
 * Messers Run
 * Negro Hollow
 * Spies Run
 * Cross Run
 * Hunkydory Creek
 * Corn Run
 * Fishing Creek
 * Montour Run
 * Hemlock Creek
 * Frozen Run
 * West Hemlock Creek
 * Little Fishing Creek
 * Spruce Run
 * West Branch Run
 * Shingle Run
 * Lick Run
 * Wolfhouse Run
 * Devil Hole Run
 * Little Brier Run
 * Stony Brook (Fishing Creek tributary)
 * Deerlick Run
 * Green Creek
 * Mud Run
 * Rickard Hollow
 * Little Green Creek
 * Huntington Creek
 * Pine Creek
 * Little Pine Creek
 * Bell Creek
 * Wasp Branch
 * Brish Run
 * Kingsbury Brook
 * Rogers Creek
 * Marsh Creek
 * Black Ash Creek
 * Marshall Hollow
 * Kitchen Creek
 * Maple Run
 * Crooked Creek
 * Boston Run
 * Maple Spring Brook
 * Shingle Cabin Brook
 * Phillips Creek
 * Lick Branch
 * Arnold Creek
 * Shingle Run
 * Laurel Run
 * Mitchler Run
 * Raven Creek
 * East Branch Raven Creek
 * Stine Hollow
 * West Creek
 * Spencer Run
 * York Hollow
 * Coles Creek
 * Hess Hollow
 * Fallow Hollow
 * Ashelman Run
 * Marsh Run
 * Chimneystack Run
 * West Branch Fishing Creek
 * Rough Run
 * Peterman Run
 * Elk Run
 * Long Run
 * Hog Run
 * Gallows Run
 * Bloody Run
 * Painter Run
 * Oxhorn Run
 * Big Run
 * Shingle Mill Run
 * Bearwallow Run
 * Deep Hollow
 * Laurel Run
 * Hemlock Run
 * Slip Run
 * Swanks Run
 * East Branch Fishing Creek
 * Blackberry Run
 * Trout Run
 * Lead Run
 * Heberly Run
 * Quinn Run
 * Shanty Run
 * Meeker Run
 * Big Run
 * Sullivan Branch
 * Pigeon Run
 * Hunts Run
 * Ore Run
 * Kinney Run
 * Tenmile Run
 * Briar Creek
 * East Branch Briar Creek
 * Glen Brook
 * Kashinka Hollow
 * West Branch Briar Creek
 * Fester Hollow
 * Cabin Run
 * Nescopeck Creek
 * Black Creek
 * Scotch Run
 * Falls Run
 * Barnes Run
 * Stony Creek (Black Creek tributary)
 * Cranberry Creek
 * Wolffs Run
 * Little Black Creek
 * Little Nescopeck Creek
 * Long Run (Nescopeck Creek tributary)
 * Oley Creek
 * Long Hollow (Oley Creek tributary)
 * Little Nescopeck Creek
 * Conety Run
 * Creasy Creek
 * Reilly Creek
 * Mill Creek
 * Salem Creek
 * Walker Run
 * Big Wapwallopen Creek
 * Balliet Run
 * Watering Run
 * Bow Creek
 * Little Wapwallopen Creek
 * Pond Creek
 * Nuangola Outlet
 * Rocky Run
 * Turtle Creek
 * Black Creek
 * Paddy Run
 * Shickshinny Creek
 * Little Shickshinny Creek
 * Reyburn Creek
 * Culver Creek
 * Hunlock Creek
 * Roaring Brook
 * Lewis Run
 * Harveys Creek
 * East Fork Harveys Creek
 * Drakes Creek
 * Pikes Creek
 * Fades Creek
 * Paint Spring Run
 * Bear Hollow Creek
 * Newport Creek
 * South Branch Newport Creek
 * Reservoir Creek
 * Middle Branch Newport Creek
 * Northbranch Newport Creek
 * Nanticoke Creek
 * Espy Run
 * Warrior Creek
 * Solomon Creek
 * Spring Run
 * Sugar Notch Run
 * Pine Creek
 * Toby Creek
 * Huntsville Creek
 * Browns Creek
 * Trout Brook
 * Mill Creek
 * Laurel Run
 * Deep Hollow
 * Gardner Creek
 * Lampblack Creek
 * Three Spring Brook
 * Deep Creek
 * Rough Hollow
 * Warden Creek
 * Abrahams Creek
 * Lackawanna River
 * Red Spring Run
 * Saint Johns Creek
 * Mill Creek
 * Lidy Creek
 * Collins Creek
 * Spring Brook
 * Covey Swamp Creek
 * Monument Creek
 * Trout Creek
 * Green Run
 * Rattlesnake Creek
 * Six Springs Creek
 * Plank Bridge Creek
 * Panther Creek
 * Painter Creek
 * Keyser Creek
 * Lindy Creek
 * Lucky Run
 * Stafford Meadow Brook
 * Roaring Brook
 * Little Roaring Brook
 * Rock Bottom Creek
 * White Oak Run
 * Kellum Creek
 * Van Brunt Creek
 * Langan Creek
 * Bear Brook
 * East Branch Roaring Brook
 * Lake Run
 * Emerson Run
 * Meadow Brook
 * Leggetts Creek
 * Leach Creek
 * South Branch Leach Creek
 * Clover Hill Creek
 * Summit Lake Creek
 * Price Creek
 * Pancoast Creek
 * Eddy Creek
 * Hull Creek
 * Wildcat Creek
 * West Branch Tinklepaugh Creek
 * Sterry Creek
 * Grassy Island Creek
 * Laurel Run
 * White Oak Run
 * Indian Cave Creek
 * Aylesworth Creek
 * Callender Gap Creek
 * Rush Brook
 * Powderly Creek
 * Lees Creek
 * Meredith Creek
 * Fall Brook
 * Racket Brook
 * Coal Brook
 * Wilson Creek
 * Rogers Brook
 * Clarks Creek
 * Meredith Brook
 * Brace Brook
 * East Branch Lackawanna River
 * West Branch Lackawanna River
 * Fiddle Lake Creek
 * Hicks Creek
 * Obendoffers Creek
 * Gardner Creek
 * Lewis Creek
 * Sutton Creek
 * Cider Run
 * Bowman Creek
 * Benson Hollow
 * Sugar Hollow Creek
 * Marsh Creek
 * Sugar Run
 * Roaring Run
 * Newton Run
 * South Branch Roaring Run
 * Leonard Creek
 * South Run
 * Beaver Run
 * Hettesheimer Run
 * York Run
 * Stone Run
 * Sorber Run
 * Baker Run
 * Windfall Run
 * Broad Hollow Run
 * Sugar Run
 * Cider Run
 * Butternut Run
 * Beth Run
 * Wolf Run
 * Bean Run
 * North Branch Bowman Creek
 * South Branch Bowman Creek
 * Cherry Run
 * Tunkhannock Creek
 * Swale Brook
 * Billings Mill Brook
 * Kern Glen Creek
 * South Branch Tunkhannock Creek
 * Trout Brook
 * Ackerly Creek
 * Kennedy Creek (Pennsylvania)Kennedy Creek
 * Oxbow Creek
 * Horton Creek
 * Oxbow Inlet
 * Monroe Creek
 * Field Brook
 * East Branch Field Brook
 * Horton Creek
 * Martins Creek
 * Hop Bottom Creek
 * Dry Creek
 * East Branch Martins Creek
 * Utley Brook
 * Willow Brook
 * East Branch Tunkhannock Creek
 * Idlewild Creek
 * Dundaff Creek
 * Tinker Creek
 * Little Creek
 * Tinker Hollow
 * Millard Creek
 * Tower Branch
 * Partners Creek
 * Nine Partners Creek
 * Butler Creek
 * Little Butler Creek
 * Leslie Creek
 * Bell Creek
 * Bear Swamp Creek
 * Rock Creek
 * Taques Creek
 * Mehoopany Creek
 * Fox Hollow
 * Rogers Hollow
 * North Branch Mehoopany Creek
 * Farr Hollow
 * Douglas Hollow
 * Burgess Brook
 * Miller Brook
 * Catlin Brook
 * Sciota Brook
 * Barnes Brook
 * Coffee Brook
 * Smith Cabin Run
 * Wolf Run
 * Bowman Hollow
 * White Brook
 * Scouten Brook
 * Kasson Brook
 * Henry Lott Brook
 * Stony Brook
 * Red Brook
 * Somer Brook
 * Becker Brook
 * South Brook
 * Opossum Brook
 * Bellas Brook
 * Cherry Ridge Run
 * Little Mehoopany Creek
 * Meshoppen Creek
 * Little Meshoppen Creek
 * West Branch Meshoppen Creek
 * Riley Creek
 * Baker Creek
 * Dority Creek
 * Nick Creek
 * White Creek
 * West Creek
 * North Branch Meshoppen Creek
 * Thomas Creek
 * Negro Hollow
 * Pond Brook
 * Stevens Creek
 * Burdick Creek
 * Tuscarora Creek
 * Sugar Run Creek
 * Sugar Run
 * Wyalusing Creek
 * North Branch Wyalusing Creek
 * Gaylord Creek
 * East Branch Wyalusing Creek
 * Wysox Creek
 * Towanda Creek
 * South Branch Towanda Creek
 * Schrader Creek
 * Sugar Creek
 * Chemung River
 * Bentley Creek
 * Seeley Creek
 * South Creek
 * Hammond Creek
 * Tioga River
 * Cowanesque River
 * Troups Creek
 * North Fork Cowanesque River
 * Crooked Creek
 * Mill Creek
 * Corey Creek
 * Elk Run
 * Cayuta Creek
 * Wappasening Creek
 * Apalachin Creek
 * Choconut Creek
 * Little Snake Creek
 * Snake Creek
 * Salt Lick Creek
 * Canawacta Creek
 * Starrucca Creek
 * Shadigee Creek

Potomac River

 * Potomac River (MD)
 * Monocacy River (MD)
 * Toms Creek
 * Middle Creek
 * Flat Run
 * Friends Creek
 * Miney Branch
 * Piney Creek
 * Alloway Creek
 * Marsh Creek
 * Willoughby Run
 * Pitzer Run
 * Rock Creek
 * White Run
 * Plum Run
 * Plum Run
 * Guinn Run
 * Winebrenner Run
 * Stevens Run
 * Blocher's Run
 * Antietam Creek
 * Marsh Run
 * East Branch Antietam Creek
 * Red Run
 * West Branch Antietam Creek
 * Conococheague Creek
 * West Branch Conococheague Creek
 * Buck Run
 * Licking Creek
 * Back Creek
 * Dennis Creek
 * Falling Spring Branch
 * Little Conococheague Creek
 * Licking Creek
 * Little Cove Creek
 * Big Cove Creek
 * Patterson Run
 * Tonoloway Creek
 * Little Tonoloway Creek
 * Sideling Hill Creek
 * Town Creek
 * Flintstone Creek
 * Sweet Root Creek
 * Elk Lick Creek
 * North Branch Potomac River (MD)
 * Evitts Creek
 * Wills Creek
 * Gladdens Run
 * Little Wills Creek
 * Brush Creek

Gulf of Mexico
(via the Mississippi River)

Ohio River

 * Ohio River
 * Fish Creek
 * Pennsylvania Fork Fish Creek
 * Flaugherty Run
 * Spring Run
 * Wheeling Creek
 * Enlow Fork
 * Robinson Fork
 * Templeton Fork
 * Dunkard Fork
 * North Fork Dunkard Fork
 * South Fork Dunkard Fork
 * Buffalo Creek
 * Castleman Run
 * Welch Run
 * Dog Run
 * Dutch Fork
 * Ralston Run
 * Bonar Creek
 * Narigan Run
 * Brush Run
 * Dunkle Run
 * Hanen Run
 * Buck Run
 * Wolf Run
 * Sawhill Run
 * Cross Creek (Ohio River tributary)
 * Scott Run
 * Parmar Run
 * North Fork Cross Creek
 * Middle Fork Cross Creek
 * Haynan Creek
 * South Fork Cross Creek
 * Harmon Creek
 * Paris Run
 * Ward Run
 * Kings Creek
 * North Fork Kings Creek
 * Aunt Clara Fork
 * Lawrence Run
 * Little Beaver Creek
 * North Fork Little Beaver Creek
 * Raccoon Creek
 * Beaver River
 * McKinley Run
 * Hamilton Run
 * Brady Run
 * Walnut Bottom Run
 * Bennett Run
 * Wallace Run
 * Thompson Run
 * Clarks Run
 * Stockman Run
 * Connoquenessing Creek
 * Slippery Rock Creek
 * Skunk Run
 * Hell Run
 * Grindstone Run
 * Cheeseman Run
 * Muddy Creek
 * Taylor Run
 * Jamison Run
 * Black Run
 * Wolf Creek
 * Hogue Run
 * Big Run
 * Glade Run
 * Long Run
 * McDonald Run
 * South Branch Slippery Rock Creek
 * McMurray Run
 * North Branch of Slippery Rock Creek
 * Blacks Creek
 * Seaton Creek
 * Brush Creek
 * Camp Run
 * Scholars Run
 * Little Connoquenessing Creek
 * Breakneck Creek
 * Likens Run
 * Wolfe Run
 * Kaufman Run
 * Glade Run
 * South Branch Glade Run
 * Thorn Creek
 * Sullivan Run
 * Bonnie Brook
 * Wampum Run
 * Snake Run
 * Eckles Run
 * Jenkins Run
 * Edwards Run
 * McKee Run
 * Mahoning River
 * Hickory Run
 * Shenango River
 * Neshannock Creek
 * Hottenbaugh Run
 * Little Neshannock Creek
 * West Branch Little Neshannock Creek
 * Potter Run
 * Indian Run
 * Hunters Run
 * Mill Run
 * Pine Run
 * Beaver Run
 * Otter Creek
 * Cool Spring Creek
 * Yellow Creek
 * Pymatuning Creek
 * Little Shenango River
 * Crooked Creek
 * Linesville Creek
 * Chartiers Creek
 * Whiskey Run
 * Campbells Run
 * Robinson Run
 * Scrubgrass Run
 * Painters Run
 * McLaughlin Run
 * Thoms Run
 * Millers Run
 * Coal Run
 * Brush Run
 * McPherson Creek
 * Little Chartiers Creek
 * Brush Run
 * Chartiers Run
 * Plum Run
 * Westland Run
 * Georges Run
 * Catfish Creek

Allegheny River

 * Allegheny River
 * Girtys Run
 * Pine Creek
 * Squaw Run
 * Plum Creek
 * Deer Creek
 * Riddle Run
 * Pucketa Creek
 * Little Pucketa Creek
 * Bull Creek
 * Little Bull Creek
 * McDowell Run
 * Lardintown Run
 * Rocky Run
 * Chartiers Run
 * Rachel Carson Run
 * Buffalo Creek
 * Little Buffalo Creek
 * Cornplanter Run
 * Patterson Creek
 * Kiskiminetas River
 * Carnahan Run
 * Beaver Run
 * Blacklegs Creek
 * Loyalhanna Creek
 * Four Mile Run
 * Mill Creek
 * Conemaugh River
 * Blacklick Creek
 * Two Lick Creek
 * Yellow Creek
 * Little Yellow Creek
 * North Branch Blacklick Creek
 * South Branch Blacklick Creek
 * Little Conemaugh River
 * South Fork Little Conemaugh River
 * Stonycreek River
 * Bens Creek
 * Paint Creek
 * Shade Creek
 * Clear Shade Creek
 * Dark Shade Creek
 * Quemahoning Creek
 * Glade Run
 * Crooked Creek
 * Plum Creek
 * North Branch Plum Creek
 * South Branch Plum Creek
 * McKee Run
 * Cowanshannock Creek
 * Pine Creek
 * Mahoning Creek
 * Canoe Creek
 * Pine Run
 * Little Mahoning Creek
 * Stump Creek
 * East Branch Mahoning Creek
 * Redbank Creek
 * Little Sandy Creek
 * North Fork Creek
 * Sandy Lick Creek
 * Mill Creek
 * Bear Creek
 * Silver Creek
 * South Branch Bear Creek
 * North Branch Bear Creek
 * Clarion River
 * Turkey Run
 * Canoe Creek
 * Licking Creek
 * Deer Creek
 * Paint Creek
 * Piney Creek
 * Toby Creek
 * Mill Creek
 * Millstone Creek
 * Spring Creek
 * Little Toby Creek
 * Bear Creek
 * Big Mill Creek
 * Elk Creek
 * Little Mill Creek
 * East Branch Clarion River
 * West Branch Clarion River
 * Scrubgrass Creek
 * Sandy Creek
 * South Sandy Creek
 * Little Sandy Creek
 * East Sandy Creek
 * French Creek
 * Sugar Creek
 * Lake Creek
 * East Branch Sugar Creek
 * North Deer Creek
 * Little Creek
 * Conneaut Outlet
 * Rock Creek
 * Williams Run
 * Watson Run
 * McMichael Run
 * Mud Run
 * Adsit Run
 * Barber Run
 * Van Horne Creek
 * Cussewago Creek
 * Bennyhoof Creek
 * Spring Run
 * Carr Run
 * Rundelltown Creek
 * West Branch Cussewago Creek
 * Gravel Run
 * Woodcock Creek
 * Conneauttee Creek
 * Little Conneauttee Creek
 * Torry Run
 * Darrows Creek
 * Shenango Creek
 * Mohawk Run
 * Muddy Creek
 * Dead Creek
 * Mackey Run
 * Federal Run
 * Navy Run
 * LeBoeuf Creek
 * South Branch French Creek
 * Horton Run
 * Bentley Run
 * Pine Run
 * Hungry Run
 * Lilley Run
 * Beaver Run
 * Slaughter Run
 * Baskin Run
 * Spencer Creek
 * Alder Run
 * West Branch French Creek
 * Bailey Brook
 * Alder Brook
 * Townley Run
 * Darrow Brook
 * Hubbel Run
 * Brannon Run
 * Charley Run
 * Oil Creek
 * Cornplanter Run
 * Cherry Run
 * Cherrytree Run
 * Benninghof Run
 * Pine Creek
 * Caldwell Creek
 * Porky Run
 * Stony Hollow Run
 * West Branch Caldwell Creek
 * Dunderdale Creek
 * Henderson Run
 * Church Run
 * Thompson Creek
 * McLaughlin Creek
 * Shirley Run
 * Dolly Run
 * Hummer Creek
 * East Branch Oil Creek
 * Mosey Run
 * East Shreve Run
 * West Shreve Run
 * Pithole Creek
 * Hemlock Creek
 * Tionesta Creek
 * Coon Creek
 * Salmon Creek
 * West Branch Tionesta Creek
 * South Branch Tionesta Creek
 * East Hickory Creek
 * Tidioute Creek
 * Brokenstraw Creek
 * Irvine Run
 * McKinney Run
 * Indian Camp Run
 * Matthews Run
 * Mead Run
 * Andrews Run
 * Little Brokenstraw Creek
 * Blue Eye Run
 * Gar Run
 * Spring Creek
 * Damon Run
 * Hare Creek
 * Coffee Creek
 * Conewango Creek
 * Stillwater Creek
 * Chadakoin River
 * Kinzua Creek
 * South Branch Kinzua Creek
 * Sugar Run
 * Tunungwant Creek
 * Latchaw Creek
 * Foster Brook
 * Harrisburg Run
 * Pennbrook Run
 * Bolivar Run
 * Kendall Creek
 * Lafferty Run
 * East Branch Tunungwant Creek
 * Rutherford Run
 * Minard Run
 * Sheppard Run
 * Watrous Run
 * Foster Run
 * West Branch Tunungwant Creek
 * Bennett Brook
 * Marilla Brook
 * Gilbert Run
 * Langmade Brook
 * Fuller Brook
 * South Penn Run
 * Kissem Run
 * Two Mile Run
 * Knapp Creek
 * Barden Brook
 * Oswayo Creek
 * Little Genesee Creek
 * Honeoye Creek
 * Potato Creek
 * Marvin Creek
 * Allegheny Portage Creek

Monongahela River

 * Monongahela River
 * Four Mile Run
 * Panther Hollow Run
 * Phipps Run
 * Becks Run
 * Streets Run
 * Glass Run
 * West Run
 * Ninemile Run
 * Turtle Creek
 * Brush Creek
 * Bushy Run
 * Thompson Run
 * Crooked Run
 * Youghiogheny River
 * Long Run
 * Crawford Run
 * Rock Run
 * Gillespie Run
 * Pollock Run
 * Sewickley Creek
 * Little Sewickley Creek
 * Kelly Run
 * Hunters Run
 * Pinkerton Run
 * Lick Run
 * Buffalo Run
 * Belson Run
 * Wilson Run
 * Jacks Run
 * Township Line Run
 * Boyer Run
 * Brinker Run
 * Welty Run
 * Cedar Creek
 * Jacobs Creek
 * Barren Run
 * Meadow Creek
 * Stauffer Run
 * Sherrick Run
 * Shupe Run
 * Brush Run
 * Laurel Run
 * Browneller Run
 * Washington Run
 * Virgin Run
 * Furnace Run
 * Smiley Run
 * Dickerson Run
 * Hickman Run
 * Galley Run
 * Mounts Creek
 * Connell Run
 * Dunbar Creek
 * Laurel Run
 * Indian Creek
 * Morgan Run
 * Workman Run
 * Johnson Run
 * Bruner Run
 * Crooked Run
 * Sugar Run
 * Jonathan Run
 * Bear Run
 * Stulls Run
 * Jim Run
 * Cucumber Run
 * Meadow Run
 * Sheepskin Run
 * Rock Spring Run
 * Lick Run
 * Camp Run
 * Drake Run
 * Ramcat Run
 * Casselman River
 * Laurel Hill Creek
 * Coxes Creek
 * Buffalo Creek
 * Flaugherty Creek
 * Hen Run
 * Tub Run
 * Hall Run
 * Braddocks Run
 * Reason Run
 * Lewis Run (Monongahela River tributary)
 * Peters Creek
 * Lewis Run (Peters Creek tributary)
 * Beam Run
 * Lick Run
 * Piney Fork
 * Wylie Run
 * Fallen Timber Run
 * Lobbs Run
 * Kelly Run (Monongahela River tributary)
 * Bunola Run
 * Houston Run
 * Mingo Creek
 * Dry Run
 * Pigeon Creek
 * Beckets Run
 * Maple Creek
 * Speers Run
 * Hooders Run
 * Little Redstone Creek
 * Redstone Creek
 * Dunlap Creek
 * Tenmile Creek
 * South Fork Tenmile Creek
 * Castile Run
 * Browns Run
 * Ruff Creek
 * Coal Lick Run
 * Grimes Run
 * Laurel Run
 * Sugar Run
 * Jackson Run
 * Purman Run
 * Smith Creek
 * Toll Gate Run
 * Browns Creek
 * Throckmorton Run
 * Clear Run
 * Pursley Creek
 * Rush Run
 * Lightner Run
 * Hargus Creek
 * West Run
 * Scott Run
 * Morris Run
 * Plum Run
 * Barrs Run
 * Daniels Run
 * Rush Run
 * Bates Run
 * Pumpkin Run
 * Muddy Creek
 * Wallace Run
 * Antram Run
 * Middle Run
 * Browns Run
 * Little Whiteley Creek
 * Whiteley Creek
 * Cats Run
 * Jacobs Creek
 * Georges Creek
 * War Branch
 * York Run
 * Mountain Creek
 * Muddy Run
 * Dunkard Creek
 * Rocky Hollow
 * Meadow Run
 * Roberts Run
 * Bell Run
 * Glade Run
 * Dooley Run
 * Calvin Run
 * Watkins Run
 * North Branch Calvin Run
 * Hobbs Run
 * Bacon Run
 * Cheat River
 * Big Sandy Creek
 * Tebolt Run
 * Quebec Run
 * McIntire Run
 * Scotts Run
 * Chaney Run
 * Braddock Run
 * Little Sandy Creek
 * Camp Run

Lake Erie

 * Twentymile Creek
 * Sixteenmile Creek
 * Twelvemile Creek
 * Eightmile Creek
 * Scott Run
 * Sevenmile Creek
 * Elliotts Run
 * Sixmile Creek
 * Fourmile Creek
 * Mill Creek
 * Walnut Creek
 * Bear Run
 * Trout Run
 * Elk Creek
 * Little Elk Creek
 * Lamson Run
 * Crooked Creek
 * Raccoon Creek
 * Turkey Creek
 * Conneaut Creek
 * East Branch Conneaut Creek
 * Temple Creek
 * West Branch Conneaut Creek

Lake Ontario

 * Genesee River
 * Cryder Creek

title: List of rivers of Pennsylvania


text:
Lehigh River

The Lehigh River is a 109 mi tributary of the Delaware River in eastern Pennsylvania. The river flows in a generally southward pattern from the Pocono Mountains in Northeastern Pennsylvania through Allentown and much of the Lehigh Valley before joining the Delaware River in Easton.

Part of the Lehigh River and a number of its tributaries are designated Pennsylvania Scenic Rivers by the state's Department of Conservation and Natural Resources.

The river's name is an anglicisation of the Lenape name for the river, Lechewuekink, which means "where there are forks". Both Lehigh County and Lehigh Valley are named for the river.

Between 1821 and 1966, the Lehigh River was owned by the Lehigh Coal and Navigation Company, making it the only privately owned river in the United States. This private ownership continued until a local representative, Samuel Frank, promoted a bill to return control of the river to the state in 1967.

According to an environmental report from a Pennsylvania nonprofit research center, the Lehigh River watershed is ranked second nationally in the volume of toxic substances released into it in 2020. The study mirrored a previous report by the state's Department of Environmental Protection that found most of the county's waterways unsafe for swimming or aquatic life.

Course
The Lehigh River flows in a highly winding course through valleys between ridges of Pennsylvania's Appalachian Mountains. Its upper course is characterized by numerous whitewater rapids and supports recreational pursuits, including rafting, kayaking, and canoeing. Its lower course forms the heart of the Lehigh Valley, a historically important anthracite coal and steel-producing region of Pennsylvania.

The river rises in the Poconos region of northeastern Pennsylvania in several ponds in Lehigh Township in Wayne County, approximately 15 mi southeast of Scranton. The PA Gazetteer of Streams shows that the Lehigh River begins as the outflow of Pocono Peak Lake. Flowing south from the south end of the lake (a natural but dammed body of water), the river turns west after a mile and receives water from many lakes and ponds as it flows past Gouldsboro.

It flows initially southwest through southern Lackawanna County and then through Francis E. Walter Dam. Near White Haven, it turns south, following a zigzag whitewater course through Lehigh Gorge State Park to Jim Thorpe, then southeast, past Lehighton. Southeast of Lehighton, it passes through Blue Mountain in the narrow opening at Lehigh Gap. A six-mile stretch of the river between Freemansburg and Easton is known as the "dry-lands" because all of the water from rain drainage flows underground.

From the Lehigh Gap, the river flows southeast to Allentown, where it is joined by Little Lehigh Creek, then northeast past Bethlehem, where it joins the Delaware River in Easton at Pennsylvania's border with northwestern New Jersey.

Fishing
The Lehigh River holds many species of fish, including trout, smallmouth bass, largemouth bass, pickerel, panfish, carp, catfish, eel, and muskie. Rainbow trout, brown trout, and brook trout in the 11"-14" range are average, while some have been caught in the 20" range. Smallmouth bass are large in numbers but are of smaller size with most between 8"-14" with an occasional fish from the 18"-21" range. There is an increasing number of muskie being reported within the 30"-52" range. There are both pure and tiger muskie, the usually sterile, hybrid offspring of the true muskellunge (Esox masquinongy) and the northern pike (Esox lucius) being caught in the river.

Over the years since 2005 various groups such as the Lehigh Coldwater Fishery Alliance and the Pennsylvania Fish and Boat Commission have worked with the Army Corps of Engineers to design annual flow plans from the Frances Walter Dam (F.E.W.) to maximize the cold water discharge through the spring and summer. This has helped enhance the population of coldwater species like brown trout to gain a growing naturally reproducing population within the river below F.E.W. dam all the way to Northampton.

Whitewater rafting and tubing
The Lehigh River is a whitewater river with Class I, II, and III rapids. The most popular section of the Lehigh River for whitewater rafting, kayaking, and canoeing is through the Lehigh Gorge State Park. The Lehigh Gorge State Park begins at the Francis E. Walter Dam and ends in Jim Thorpe. Several white water outfitters operate guided white water rafting trips in various sections of the river. The first rafting outfitter on the Lehigh River was Whitewater Challengers, which was founded in 1975. Water releases from the Francis E. Walter Dam provide enough water to make the river deep enough for boating. Three popular boating trips on the Lehigh River are:
 * White Haven to Rockport – 8.7 miles
 * Rockport to Glen Onoko – 12.2 miles
 * White Haven to Glen Onoko – 20.9 miles

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

title: Lehigh River


text:
Metropolitan Borough of Rotherham

The Metropolitan Borough of Rotherham is a metropolitan borough of South Yorkshire, England. It is named after its main settlement of Rotherham. The wider borough spans a larger area and covers the outlying towns of Maltby, Swinton, Wath-upon-Dearne, Dinnington. As well as the villages of Rawmarsh and Laughton. A large valley spans the entire borough and is referred to as the "Rother Valley".

The district was formed on 1 April 1974, under the Local Government Act 1972, as a merger of the County Borough of Rotherham, with Maltby, Rawmarsh, Swinton and Wath-upon-Dearne urban districts along with Rotherham Rural District and Kiveton Park Rural District.

Rotherham Metropolitan Borough Council is one of the safest Labour councils in the United Kingdom, although the number of Labour council seats dropped from 92% to 79% in 2014 following the Rotherham child sexual exploitation scandal.

Geography
Settlements in the borough of Rotherham include:

 * Anston, Aston, Aughton
 * Bramley, Brampton, Brampton-en-le-Morthen, Brinsworth, Brecks, Brookhouse, Broom
 * Canklow, Carr, Catcliffe, Clifton
 * Dinnington
 * East Dene, East Herringthorpe, Eastwood
 * Firbeck, Flanderwell
 * Gildingwells, Greasbrough
 * Harthill, Harley, Hellaby, Herringthorpe
 * Kimberworth, Kimberworth Park, Kiveton Park
 * Laughton-en-le-Morthen, Letwell
 * Maltby, Manvers, Masbrough, Moorgate, Morthen
 * Parkgate
 * Ravenfield, Rawmarsh, Ryecroft
 * Scholes, Slade Hooton, Stone Swallownest, Swinton, Sunnyside
 * Templeborough, Thorpe Hesley, Thorpe Salvin, Thrybergh, Thurcroft, Todwick, Treeton
 * Ulley
 * Wales, Wath-upon-Dearne, Waverley, Wellgate, Wentworth, West Melton, Whiston, Wickersley, Woodsetts

The borough borders City of Sheffield, Metropolitan Borough of Barnsley, City of Doncaster, Bassetlaw District in Nottinghamshire and North East Derbyshire and Bolsover District in Derbyshire. The borough is also close to the cities of Sheffield, Doncaster, Lincoln, Hull, Leeds, Bradford, Wakefield, Nottingham, Manchester and Derby.

Ethnicity
As of 2021, the Metropolitan Borough of Rotherham's population was enumerated at 265,807, and its ethnic makeup was 91% White, 5.3% Asian, 1.4% Mixed, 1.1% Black, 0.8% Other and 0.3% Arab. The Borough's religious makeup was 51.6% Christian, 42% No Religion, 5.3% Muslim, and has small Hindu and Sikh communities.

Council elections
The Metropolitan Borough of Rotherham was founded in 1974, and Labour have been in control of the council since the first election.

title: Metropolitan Borough of Rotherham


text:
SSK

SSK may refer to:
 * Sosyal Sigorta Kurumu, the former name of Sosyal Güvenlik Kurumu
 * SSK (hull classification symbol), denoting a diesel-powered attack submarine
 * SSK Industries, firearm manufacturer
 * Mercedes-Benz SSK, a 1930s car
 * Sentral di Sindikatonan di Korsou, the Trade Union Centre of Curaçao
 * Sistema Simvolicheskogo Kodirovanija, an assembly language for Minsk family of computers
 * Sociology of scientific knowledge
 * Selånger SK, sports club in Sweden
 * Selånger SK Bandy
 * Selånger FK
 * Sandslåns SK, sports club in Sweden
 * Sunnanå SK, sports club in Sweden
 * Södertälje SK, ice hockey club in Sweden
 * Slovene Union, Italian political party
 * SSK (Shimizu Shokuin Kaisha), a Japanese manufacturing company specializing in canned seafood goods

title: SSK


text:
City of Doncaster

The City of Doncaster is a metropolitan borough with city status in South Yorkshire, England. It is named after its principal settlement, Doncaster, and includes the surrounding suburbs of Doncaster as well as numerous towns and villages. The district has large amounts of countryside; at 219 sqmi, it is the largest metropolitan borough in England by area.

The largest settlement in the borough are Doncaster itself, followed by the towns of Thorne, Hatfield and Mexborough (the latter of which is part of the Barnsley/Dearne Valley built-up area), and it additionally covers the towns of Conisbrough, Stainforth, Bawtry, Askern, Edlington and Tickhill.

Doncaster borders North Yorkshire to the north, the East Riding of Yorkshire to the north-east, North Lincolnshire to the east, Bassetlaw in Nottinghamshire to the south-east, Rotherham to the south-west, Barnsley to the west, and Wakefield, West Yorkshire, to the north-west. It is part of the Yorkshire and the Humber region.

The borough was created on 1 April 1974, under the Local Government Act 1972, as a merger of the former County Borough of Doncaster, the urban districts of Adwick-le-Street, Bentley with Arksey, Conisbrough, Mexborough, and Tickhill, Doncaster and Thorne rural districts, and the parish of Finningley from East Retford Rural District and small parts of the parish of Harworth from Worksop Rural District from Nottinghamshire.

Population statistics
According to the 2011 census, the population of the Metropolitan Borough of Doncaster is 302,400.

With approximately 110,000 inhabitants, the town of Doncaster itself contains around a third of the population of the entire borough. Around half of the borough's population reside within Doncaster's urban area (approximately 160,000).

Verified population statistics per Ward from the 2001 census are shown as

Elected mayor
A referendum was held in 2001, to decide if a directly elected mayor should be appointed. The first mayor, Martin Winter, representing the Labour Party, was elected in 2002 and successfully defended his post in 2005.

In 2009 the English Democrat candidate, Peter Davies, won the election for mayor. In January 2013 Davies left the English Democrats citing "a big influx of new members (of the English Democrats) joining from the British National Party". In the May 2013 mayoral election he was defeated by Labour's Ros Jones.

Borough council
The council as a whole has been dominated by the Labour Party traditionally, but in the 2004 local elections, they lost overall control of the council (though they retained more councillors than any other single party). Labour regained overall control at the 2010 local elections.

2010 Audit Commission report and central government intervention
In January 2010, the Audit Commission initiated a corporate governance inspection of Doncaster Council. This followed the sudden resignation of the Chief executive leading to a conflict between the mayor and council over the appointment of a successor. The Commission felt that this, along with evidence that the council had not been well run for 15 years, was leading to a loss of public confidence.

The Commission's report was issued in April 2010. It found that Doncaster was a dysfunctional authority and that there were three factors preventing the council from providing good governance:
 * The councillors' attempts to undermine the authority of the mayor and cabinet. There was evidence that councillors had never accepted the mayoral system and tried to use their overview and scrutiny powers to frustrate the mayor's policy objectives. In February 2010, the council had rejected the mayor's budget and voted in favour of their own proposals.
 * The lack of effective leadership shown by the mayor and cabinet. The mayor was described as "not averse to provocative and inflammatory statements" and it was felt that he "does not always act in a way which demonstrates the need for an elected mayor to lead his authority and represent all the people in Doncaster".
 * The failure of chief officers to deliver effectively services. Some senior officers were found to acquiesce in the councillors' misuse of scrutiny powers. There was also a lack of trust and impartiality.

On the recommendations of the commission, the Secretary of State for Communities and Local Government, John Denham, used powers to appoint an acting chief executive and an advisory board to oversee the council. A Doncaster Recovery Board, comprising four appointed commissioners and seven other members including the mayor and chief executive held its first quarterly meeting on 10 September 2010.

Places
Settlements in the Borough of Doncaster include:

 * Adwick-le-Street, Almholme, Arksey, Armthorpe, Askern, Auckley, Austerfield
 * Balby, Barnburgh, Barnby Dun, Bawtry, Belle Vue, Bentley, Bessacarr, Blaxton, Braithwaite, Braithwell, Branton, Brodsworth, Burghwallis
 * Cadeby, Campsall, Cantley, Carcroft, Clayton, Clifton, Conisbrough, Cusworth
 * Denaby, Doncaster, Dunscroft, Dunsville
 * Edenthorpe, Edlington
 * Fenwick, Finningley, Fishlake
 * Hampole, Harlington, Hatfield, Hatfield Woodhouse, Hayfield, Haywood, Hexthorpe, Highfields, Hickleton, High Levels, High Melton, Hooton Pagnell, Hyde Park
 * Intake
 * Kirk Sandall, Kirk Bramwith
 * Lakeside, Lindholme, Loversall
 * Marr, Mexborough, Micklebring, Moorends, Moss
 * New Rossington, Norton
 * Owston
 * Rossington
 * Scawsby, Scawthorpe, Shaftholme, Skelbrooke, Skellow, Sprotbrough, Stainforth, Stainton, South Yorkshire, Sykehouse
 * Thorne, Thorpe in Balne, Tickhill, Tilts, Toll Bar, Town Moor
 * Wadworth, Warmsworth, West Bessacarr, Wheatley, Wheatley Hills, Woodlands

Media
In terms of television, the area is served by BBC Yorkshire and ITV Yorkshire broadcasting from the Emley Moor transmitter.

Radio stations that can be received in Doncaster are Sine FM 102.6 (serving central districts of around 100,000 households in FM stereo), TMCR 95.3 (which serves Northeast Doncaster and other areas in FM stereo), TX1 Radio (covering Doncaster and Bassetlaw), Capital Yorkshire, Heart Yorkshire, Greatest Hits Radio Yorkshire, Hallam FM and BBC Radio Sheffield. Although the above stations can be received within various areas of Doncaster, the only stations actually owned by Doncaster-based companies are Sine FM 102.6 and TMCR 95.3.

The borough is also the base of Nova Productions who produce the syndicated TV series Walks Around Britain.

Freedom of the Borough
The following people and military units have received the Freedom of the Borough of Doncaster.

Individuals

 * 8 July 1751: Viscount Downe, British Politician.
 * 8 July 1751: Lord Rockingham, British Prime Minister.
 * 8 July 1751: Lord Granby, British Army Officer.
 * 23 September 1806: Prince of Wales.
 * 23 September 1806: Duke of Clarence.
 * 17 September 1822: Duke of Sussex
 * 15 September 1829: FM Duke of Wellington, British Army Officer and Later Prime Minister.
 * 14 August 2017: Lance Bombardier Ben Parkinson, British Paratrooper wounded in Afghanistan.
 * 25 February 2019: Tony Sockett, Former Mayor of Doncaster.
 * 22 March 2019: Yvonne Woodcock, Mayor of Doncaster 1998–1999.
 * 22 March 2022: James Coppinger, Footballer for Doncaster Rovers 2004–2021.
 * 13 July 2023: Rt Hon Lord Kirkham, British Businessman and Politician.

Military Units

 * The King's Own Yorkshire Light Infantry: 1945.
 * RAF Finningley: 1975.
 * The Rifles: 8 September 2007.
 * The Coldstream Guards: 15 July 2021.

title: City of Doncaster


text:
Talk:Search algorithm

Wiki Education Foundation-supported course assignment
This article was the subject of a Wiki Education Foundation-supported course assignment, between 20 January 2021 and 2 May 2021. Further details are available on the course page. Student editor(s): Rjrno3300.

Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 08:50, 17 January 2022 (UTC)

Search broken
Can anyone help? For some reason our wiki search does not return any results.

Even if I search for the exact wiki page - no results are displayed.

Last week it was working fine and produced the correct results. I have checked with our

Systems Administrator and had confirmation that nothing was changed over the weekend.

Thanks in advance for your help lenaquin@orbisuk.com — Preceding unsigned comment added by Lenaquin (talk • contribs) 10:25, 25 July 2005 (UTC)

 * This is the wrong page to ask about Wikipedia's search engine; this talk page is for discussing improvements to the Wikipedia article Search algorithm. If the question is about a local copy of Mediawiki, the place to go is probably the mediawiki.org web site. -- Beland (talk) 05:25, 8 August 2016 (UTC)

Combinatorial Search
(This notice also posted to Talk: Combinatorial search) How much overlap does this page have with combinatorial search? Do they deserve a merging? Is one of these article titles inappropriate? Should one link to the other?

Derrick Coetzee 21:31, 4 May 2004 (UTC)

 * Combinatorial Search Algorithms are a subset of Search Algorithms; Combinatorial Search could refer to the search problem rather than the algorithm used to solve it. The two articles should not be merged or directly linked. Headstogether 13:47, 8 November 2005 (UTC)

Grover's Algorithm
The mention of Grover's Algorithm, and quantum computing is somewhat misleading. It states that Grover's algorithm 'provides a solution' in polynomial time. It does no such thing: It is a theoretical model of a non-existant computing system. Maybe some day there will be quantum computers, but until then, an algorithm that runs only on a non-existant quantum computer exists only in the realm of theory.AngleWyrm 05:20, 10 August 2007 (UTC)

Quantum
Quantum computers exist now, and one has been sold commercially. 19:56, 10 September 2011 (UTC) — Preceding unsigned comment added by 108.194.44.134 (talk)

Removed
Removed the questionable sections on "SQL search" and "tradeoff search", which are subtopics at best. Bryan Silverthorn (talk) 20:56, 10 December 2007 (UTC)

Some missing points
Pgr94 (talk) 10:42, 15 April 2008 (UTC)
 * relationship between search and optimisation
 * local vs global search, local optima
 * soundness and completeness of search

General reorganization
The topic "search algorithm" is too vast to discuss in detail in a single article, so I have reorganized it into an overview of the major classes of search problems and algorithms, with only a few *examples* of each class. Detailed discussions, such as complexity or applications, are best left to the articles on individual caetgories or individual methods. The material that could not be used is temproarily copied below. It should be merged eventually into the relevant articles, such as linear search and tree search algorithm.

 * List search
 * Lists, and sequences generally, are perhaps the most commonly encountered data structures; search algorithms adapted for them are common as well. The goal is to find one element of a set (i.e., from the list) by some criterion (typically called a key and perhaps containing other information related to it). As this is a common problem in computer science, the computational complexity of these algorithms has been intensively studied.

 * The simplest such algorithm is linear search, which examines each element of the list as they are encountered. It is expensive in running time compared to many other algorithms: in O(n), where n is the number of items in the list. It can be used directly on any unprocessed list, regardless of history, which is sometimes useful. A more sophisticated list search algorithm is binary search; it runs in O(log n) time.  This is significantly better than linear search for large lists, but is sometimes useful for surprisingly small ones given its increase in speed. But it requires the list be sorted before searching (see sorting algorithm) and generally, that the list be randomly accessible. This last may force lengthy (ie, time expensive) reads of mass storage before a binary search can be started. Interpolation search is better than binary search for large sorted lists with 'fairly even' key distributions (O(log (log n)) complexity), but has a worst-case running time of O(n).

 * Hash tables can also be used for list searches. They run in constant time in the average case, but have terrible worst-case time (O(n)) In addition, more space and time is required to set up such tables. Another search based on specialized data structures uses self-balancing binary search trees and needs only O(log n) time. Such tree searches can be seen as extending the ideas of binary search to allow fast insertion and removal in the data structures. See associative array for more discussion of list search data structures.

 * Most list search algorithms, such as linear search, binary search, and self-balancing binary search trees, can be extended with little additional cost to find all values less than or greater than a given key, an operation called range search. One such exception is hash tables, which cannot perform such searches efficiently.

 * Tree search
 * Tree search algorithms are likely the most used searching techniques for structured data. They examine trees of nodes, whether the tree is explicit or implicit (ie, generated by the search algorithm's execution). The basic principle is that a node is taken from a data structure, its successors examined and added to the data structure. By manipulating the data structure, the tree can be explored in different orders. For instance, level by level (ie, breadth-first search) or reaching a leaf node first and backtracking (ie, depth-first search), etc. Other examples of tree-searches include iterative-deepening search, depth-limited search, bidirectional search, and uniform-cost search.

 * The efficiency of a tree search is highly dependent upon the number and structure of nodes in relation to the number of items on that node. If there are a large number of items on one or more nodes, there may well be a requirement to use a specific different search technique for locating items within that particular set to attain adequate performance. In other words, a tree search is not mutually exclusive with any other search technique that may be used for specific sets. It is a method of reducing the number of relevant items to be searched to those within certain branches of the tree, thus reducing running time. For example, the Greater London telephone directory may contain entries for 20,000+ people whose surname is 'Smith' belonging on a tree branch on which are found 'surnames beginning S'. The list of names may, or may not be, further ordered (ie, structured) by subscribers first names or initials. A binary search may be appropriate to locate a particular person with given name 'Alice' and perhaps thereafter a linear search to locate a particular address for a specific Alice Smith.

 * See also
 * Ternary search
 * Search suggest drop-down list
 * Secretary problem is an online (i.e. sequentially presented) search problem with imperfect information, and a statistically optimal strategy
 * Odds algorithm is a general online search–selection algorithm for random input.
 * Princess and monster game

All the best, --Jorge Stolfi (talk) 17:58, 4 January 2010 (UTC)

Missing section(s)
adversarial search redirects here, but there is nothing in the article about it. —Preceding unsigned comment added by 134.71.47.130 (talk) 22:07, 9 February 2011 (UTC)

Algorithms discussion - can we make this more exhaustive and hierarchical?
There exists a wide expanse of algorithm and discussion on wikipedia. But it's difficult to find a lot of them without finding them first on some other discussion site. Therefore, I suggest (and I'm doing it here since I could not get to the 'talk' section of 'algorithm' page on wikipedia) that we collect all the algorithms we have on here, and make them hierarchical by category. What I mean is, Algorithm page -> sub-topics: search algorithms, sorting algorithms, graph algorithms, generic algorithms, etc. Generic Algorithms -> sub-topics-generic programming algorithms: arrays, lists, linked lists, etc. Search algorithms -> sub-topics: disk-based searching, in-memory searching Graph algorithms -> sub-topics: Sorting algorithms -> sub-topics:

You get the idea. This way, if people are wanting to discover what's new or what's old, where we've been and where things are going, or just want to endulge themselves in algorithms and computer techniques, they can just start at one of these pages and work their way down to more detailed discussions from there. These should all go back to the 'algorithm' page on wikipedia, as a starting point. 'See also' at the bottom of course can still link to related topics....

Just a suggestion that would make wikipedia's algorithms arsenal more efficient to find and search/browse through... 75.133.175.2 (talk) 06:29, 30 October 2013 (UTC)

Calling for expert attention
This article is stalled at a level of expertise and degree of quality of organization and sourcing that is markedly subpar, and so I have called for expert attention. The article has for some time been essentially a hodgepodge listing of various ideas and approaches in the subject area, strung together as Wikilinks, rather than a well-structured, externally sourced encyclopedic article.

As well, the only source currently listed, Knuth (at Stanford, reference to which I completed today, to make fully accessible)--while a fine starting point--does not appear anywhere as an inline citation, and is, at this point in time, over 15 years old. This, I would note, is a significant percentage of the overall lifetime of the subject matter's history itself.

Bottom line, the article needs to be re-structured by an expert, with standard contemporary academic sources added, with much of the extraneous linked material removed, so that it is a stand-alone, substantive encyclopedia article useful to a lay-reader. Leprof 7272 (talk) 16:48, 13 December 2014 (UTC)

title: Talk:Search algorithm


text:
Metropolitan Borough of Barnsley

The Metropolitan Borough of Barnsley is a metropolitan borough in South Yorkshire, England; the main settlement is Barnsley and other notable towns include Penistone, Wombwell and Hoyland.

The borough is bisected by the M1 motorway; it is rural to the west, and largely urban/industrial to the east it is estimated that around 16% of the Borough is classed as Urban overall with this area being home to a vast majority of its residents. Additionally 68% of Barnsley's 32,863 hectares is green belt and 9% is national park land, the majority of which is west of the M1. In 2007 it was estimated that Barnsley had 224,600 residents, measured at the 2011 census as 231,221.

The neighbouring districts are Doncaster, Rotherham, Sheffield, High Peak, Kirklees and Wakefield.

History
The borough was created on 1 April 1974 under the Local Government Act 1972. It covered the whole area of 12 former districts and parts of another two, which were all abolished at the same time:

 * Barnsley County Borough
 * Cudworth Urban District
 * Darfield Urban District
 * Darton Urban District
 * Dearne Urban District
 * Dodworth Urban District
 * Hemsworth Rural District (part, being the parishes of Billingley, Brierley, Great Houghton, Little Houghton and Shafton)
 * Hoyland Nether Urban District
 * Penistone Rural District
 * Penistone Urban District
 * Royston Urban District
 * Wombwell Urban District
 * Worsbrough Urban District
 * Wortley Rural District (part, being the parishes of Tankersley and Wortley)

The county borough of Barnsley had been self-governing, whereas the other 13 districts were all lower-tier authorities where county-level services were provided by West Riding County Council.

From its creation in 1974 until 1986, the Metropolitan Borough of Barnsley was a district-level authority, with county-level services provided by South Yorkshire County Council. The county council was abolished in 1986, since when Barnsley has been responsible for all local government services.

The borough forms part of the South Yorkshire Mayoral Combined Authority.

Governance
Elections to the council are held in three out of every four years, with one third of the 63 councillors being elected at each election. The council has been controlled by the Labour Party since its creation in 1974.

The borough council appoints one councillor to be the mayor every year. On the day of the mayor's appointment, a parade takes place in front of the town hall in honour of the new mayor.

Barnsley borough is represented by four MPs: Dan Jarvis for Barnsley Central (Labour), Miriam Cates for Penistone & Stocksbridge (Conservative), Stephanie Peacock for Barnsley East (Labour) and John Healey for Wentworth and Dearne CC (Labour).

Towns, wards and villages

 * Ardsley, Athersley
 * Barnsley, Barugh, Barugh-Green, Billingley, Birdwell, Bolton upon Dearne, Brierley
 * Cortonwood, Carlecotes, Carlton, Cawthorne, Cubley, Cudworth
 * Darfield, Darton, Dodworth, Dunford Bridge
 * Elsecar
 * Gawber, Gilroyd, Goldthorpe, Great Houghton, Grimethorpe
 * Haigh (half in Wakefield district), Hemingfield, High Hoyland, Higham, Honeywell, Hood Green, Hoyland, Hoylandswaine
 * Ingbirchworth
 * Jump
 * Kendray, Kexbrough, Kingstone
 * Little Houghton, Lundwood
 * Mapplewell, Millhouses, Millhouse Green, Monk Bretton
 * New Lodge
 * Old Town, Oxspring
 * Platts Common, Penistone, Pilley, Pogmoor
 * Royston, Redbrook
 * Shafton, Silkstone, Silkstone Common, Smithies, Staincross, Stairfoot
 * Tankersley, Thurgoland, Thurlstone, Thurnscoe
 * Ward Green, Wilthorpe, Woolley Colliery, Wombwell, Wortley, Worsbrough

There are many Hoylands in Barnsley – there is the village of Hoyland itself south-east of Barnsley on the road to Sheffield, which includes the former hamlets of Hoyland Common, Upper Hoyland and Hoyland Nether (nether being old English for "lower"). Hoylandswaine is located on the opposite side of the wide valley, and at almost 1000 feet above sea level has a wilder and bleaker feel than High Hoyland. The word Hoyland is derived from Norse, and at its simplest means "farm on a hill". Despite there being countless farms on hills around England, the majority of the Hoylands are concentrated in Barnsley.

Education
There are over 100 schools and colleges in the borough. State education is managed by Barnsley Local Education Authority. There are 14 state-run secondary schools and around 80 primary schools. There was an independent school, Hope House School. Post-16 education is provided at Barnsley College and the sixth form of Penistone Grammar School. An adult education college, Northern College, is located at Wentworth Castle in Stainborough. The University of Huddersfield has a campus in Barnsley town centre.

Media
In terms of television, the area is served by BBC Yorkshire and ITV Yorkshire broadcasting from the Emley Moor transmitter.

Radio stations for the area are:

BBC Local Radio

 * BBC Radio Sheffield

Independent Local Radio

 * Heart Yorkshire
 * Capital Yorkshire
 * Hallam FM
 * Greatest Hits Radio South Yorkshire (formerly Dearne FM)

Community Radio

 * Penistone FM (serving Penistone and Stocksbridge)

Local newspaper for the area is served by the Barnsley Chronicle.

Places of interest

 * Cannon Hall
 * Cannon Hall Farm
 * Elsecar Heritage Centre
 * Monk Bretton Priory
 * Barnsley Town Hall
 * Lowe Stand

Places of concern

 * Boulder Bridge

title: Metropolitan Borough of Barnsley


text:
Unified neutral theory of biodiversity

The unified neutral theory of biodiversity and biogeography (here "Unified Theory" or "UNTB") is a theory and the title of a monograph by ecologist Stephen P. Hubbell. It aims to explain the diversity and relative abundance of species in ecological communities. Like other neutral theories of ecology, Hubbell assumes that the differences between members of an ecological community of trophically similar species are "neutral", or irrelevant to their success. This implies that niche differences do not influence abundance and the abundance of each species follows a random walk. The theory has sparked controversy,  and some authors consider it a more complex version of other null models that fit the data better.

"Neutrality" means that at a given trophic level in a food web, species are equivalent in birth rates, death rates, dispersal rates and speciation rates, when measured on a per-capita basis. This can be considered a null hypothesis to niche theory. Hubbell built on earlier neutral models, including Robert MacArthur and E.O. Wilson's theory of island biogeography and Stephen Jay Gould's concepts of symmetry and null models.

An "ecological community" is a group of trophically similar, sympatric species that actually or potentially compete in a local area for the same or similar resources. Under the Unified Theory, complex ecological interactions are permitted among individuals of an ecological community (such as competition and cooperation), provided that all individuals obey the same rules. Asymmetric phenomena such as parasitism and predation are ruled out by the terms of reference; but cooperative strategies such as swarming, and negative interaction such as competing for limited food or light are allowed (so long as all individuals behave alike).

The theory predicts the existence of a fundamental biodiversity constant, conventionally written θ, that appears to govern species richness on a wide variety of spatial and temporal scales.

Saturation
Although not strictly necessary for a neutral theory, many stochastic models of biodiversity assume a fixed, finite community size (total number of individual organisms). There are unavoidable physical constraints on the total number of individuals that can be packed into a given space (although space per se isn't necessarily a resource, it is often a useful surrogate variable for a limiting resource that is distributed over the landscape; examples would include sunlight or hosts, in the case of parasites).

If a wide range of species are considered (say, giant sequoia trees and duckweed, two species that have very different saturation densities), then the assumption of constant community size might not be very good, because density would be higher if the smaller species were monodominant. Because the Unified Theory refers only to communities of trophically similar, competing species, it is unlikely that population density will vary too widely from one place to another.

Hubbell considers the fact that community sizes are constant and interprets it as a general principle: large landscapes are always biotically saturated with individuals. Hubbell thus treats communities as being of a fixed number of individuals, usually denoted by J.

Exceptions to the saturation principle include disturbed ecosystems such as the Serengeti, where saplings are trampled by elephants and Blue wildebeests; or gardens, where certain species are systematically removed.

Species abundances
When abundance data on natural populations are collected, two observations are almost universal:

 * The most common species accounts for a substantial fraction of the individuals sampled;
 * A substantial fraction of the species sampled are very rare. Indeed, a substantial fraction of the species sampled are singletons, that is, species which are sufficiently rare for only a single individual to have been sampled.

Such observations typically generate a large number of questions. Why are the rare species rare? Why is the most abundant species so much more abundant than the median species abundance?

A non neutral explanation for the rarity of rare species might suggest that rarity is a result of poor adaptation to local conditions. The UNTB suggests that it is not necessary to invoke adaptation or niche differences because neutral dynamics alone can generate such patterns.

Species composition in any community will change randomly with time. Any particular abundance structure will have an associated probability. The UNTB predicts that the probability of a community of J individuals composed of S  distinct species with abundances $$n_1$$ for species 1, $$n_2$$ for  species 2, and so on up to $$n_S$$ for species S is given by

\Pr(n_1,n_2,\ldots,n_S| \theta, J)= \frac{J!\theta^S} { 1^{\phi_1}2^{\phi_2}\cdots J^{\phi_J} \phi_1!\phi_2!\cdots\phi_J! \Pi_{k=1}^J(\theta+k-1) } $$

where $$\theta=2J\nu$$ is the fundamental biodiversity number ($$\nu$$ is the speciation rate), and $$\phi_i$$ is the number of species that have i individuals in the sample.

This equation shows that the UNTB implies a nontrivial dominance-diversity equilibrium between speciation and extinction.

As an example, consider a community with 10 individuals and three species "a", "b", and "c" with abundances 3, 6 and 1 respectively. Then the formula above would allow us to assess the likelihood of different values of θ. There are thus S = 3 species and $$\phi_1=\phi_3=\phi_6=1$$, all other $$\phi$$'s being zero. The formula would give

\Pr(3,6,1| \theta,10)= \frac{10!\theta^3}{ 1^1\cdot 3^1\cdot 6^1 \cdot 1!1!1! \cdot \theta(\theta+1)(\theta+2)\cdots(\theta+9)} $$

which could be maximized to yield an estimate for θ (in practice, numerical methods are used). The maximum likelihood estimate for θ is about 1.1478.

We could have labelled the species another way and counted the abundances being 1,3,6 instead (or 3,1,6, etc. etc.). Logic tells us that the probability of observing a pattern of abundances will be the same observing any permutation of those abundances. Here we would have

 * $$\Pr(3;3,6,1)=\Pr(3;1,3,6)=\Pr(3;3,1,6)$$

and so on.

To account for this, it is helpful to consider only ranked abundances (that is, to sort the abundances before inserting into the formula). A ranked dominance-diversity configuration is usually written as $$\Pr(S;r_1,r_2,\ldots,r_s,0,\ldots,0)$$ where $$r_i$$ is the abundance of the ith most abundant species: $$r_1$$ is the abundance of the most abundant, $$r_2$$ the abundance of the second most abundant species, and so on. For convenience, the expression is usually "padded" with enough zeros to ensure that there are J species (the zeros indicating that the extra species have zero abundance).

It is now possible to determine the expected abundance of the ith most abundant species:

E(r_i)=\sum_{k=1}^C r_i(k)\cdot \Pr(S;r_1,r_2,\ldots,r_s,0,\ldots,0) $$

where C is the total number of configurations, $$r_i(k)$$ is the abundance of the ith ranked species in the kth configuration, and $$Pr(\ldots)$$ is the dominance-diversity probability. This formula is difficult to manipulate mathematically, but relatively simple to simulate computationally.

The model discussed so far is a model of a regional community, which Hubbell calls the metacommunity. Hubbell also acknowledged that on a local scale, dispersal plays an important role. For example, seeds are more likely to come from nearby parents than from distant parents. Hubbell introduced the parameter m, which denotes the probability of immigration in the local community from the metacommunity. If m = 1, dispersal is unlimited; the local community is just a random sample from the metacommunity and the formulas above apply. If m < 1, dispersal is limited and the local community is a dispersal-limited sample from the metacommunity for which different formulas apply.

It has been shown that $$\langle \phi_n \rangle $$, the expected number of species with abundance n, may be calculated by

\theta\frac{J!}{n!(J-n)!} \frac{\Gamma(\gamma)}{\Gamma(J+\gamma)} \int_{y=0}^\gamma \frac{\Gamma(n+y)}{\Gamma(1+y)} \frac{\Gamma(J-n+\gamma-y)}{\Gamma(\gamma-y)} \exp(-y\theta/\gamma)\,dy $$

where θ is the fundamental biodiversity number, J the community size, $$\Gamma$$ is the gamma function, and $$\gamma=(J-1)m/(1-m)$$. This formula is an approximation. The correct formula is derived in a series of papers, reviewed and synthesized by Etienne and Alonso in 2005:

\frac{\theta }{(I)_{J}} {J \choose n} \int_{0}^{1}(Ix)_{n}(I(1-x))_{J-n}\frac{(1-x)^{\theta -1}}{x}\,dx $$

where $$I = (J-1)*m/(1-m)$$ is a parameter that measures dispersal limitation.

$$\langle \phi_n \rangle$$ is zero for n > J, as there cannot be more species than individuals.

This formula is important because it allows a quick evaluation of the Unified Theory. It is not suitable for testing the theory. For this purpose, the appropriate likelihood function should be used. For the metacommunity this was given above. For the local community with dispersal limitation it is given by:

\Pr(n_1,n_2,\ldots,n_S| \theta, m, J)= \frac{J!}{\prod_{i=1}^{S}n_{i} \prod_{j=1}^{J}\Phi_{j}!}\frac{\theta ^{S}}{(I)_{J}} \sum_{A=S}^{J}K(\overrightarrow{D},A)\frac{I^{A}}{(\theta) _{A}} $$

Here, the $$K(\overrightarrow{D},A)$$ for $$A=S,...,J$$ are coefficients fully determined by the data, being defined as

K(\overrightarrow{D},A):=\sum_{\{a_{1},...,a_{S}|\sum_{i=1}^{S}a_{i}=A\}} \prod_{i=1}^{S}\frac{\overline{s}\left( n_{i},a_{i}\right) \overline{s} \left( a_{i},1\right) }{\overline{s}\left( n_{i},1\right) } $$

This seemingly complicated formula involves Stirling numbers and Pochhammer symbols, but can be very easily calculated.

An example of a species abundance curve can be found in Scientific American.

Stochastic modelling of species abundances
UNTB distinguishes between a dispersal-limited local community of size $$J$$ and a so-called metacommunity from which species can (re)immigrate and which acts as a heat bath to the local community. The distribution of species in the metacommunity is given by a dynamic equilibrium of speciation and extinction. Both community dynamics are modelled by appropriate urn processes, where each individual is represented by a ball with a color corresponding to its species. With a certain rate $$r$$ randomly chosen individuals reproduce, i.e. add another ball of their own color to the urn. Since one basic assumption is saturation, this reproduction has to happen at the cost of another random individual from the urn which is removed. At a different rate $$\mu$$ single individuals in the metacommunity are replaced by mutants of an entirely new species. Hubbell calls this simplified model for speciation a point mutation, using the terminology of the Neutral theory of molecular evolution. The urn scheme for the metacommunity of $$J_M$$ individuals is the following.

At each time step take one of the two possible actions :

 * 1) With probability $$(1-\nu)$$ draw an individual at random and replace another random individual from the urn with a copy of the first one.
 * 2) With probability $$\nu$$ draw an individual and replace it with an individual of a new species.

The size $$J_M$$ of the metacommunity does not change. This is a point process in time. The length of the time steps is distributed exponentially. For simplicity one can assume that each time step is as long as the mean time between two changes which can be derived from the reproduction and mutation rates $$r$$ and $$\mu$$. The probability $$\nu$$ is given as $$\nu=\mu/(r+\mu)$$.

The species abundance distribution for this urn process is given by Ewens's sampling formula which was originally derived in 1972 for the distribution of alleles under neutral mutations. The expected number $$S_M(n)$$ of species in the metacommunity having exactly $$n$$ individuals is:

S_M(n) = \frac{\theta}{n}\frac{\Gamma(J_M+1)\Gamma(J_M+\theta-n)}{\Gamma(J_M+1-n)\Gamma(J_M+\theta)} $$

where $$\theta=(J_M-1)\nu/(1-\nu)\approx J_M\nu$$ is called the fundamental biodiversity number. For large metacommunities and $$n\ll J_M$$ one recovers the Fisher Log-Series as species distribution.

S_M(n) \approx \frac{\theta}{n} \left( \frac{J_M}{J_M+\theta} \right)^n $$

The urn scheme for the local community of fixed size $$J$$ is very similar to the one for the metacommunity.

At each time step take one of the two actions :

 * 1) With probability $$(1-m)$$ draw an individual at random and replace another random individual from the urn with a copy of the first one.
 * 2) With probability $$m$$ replace a random individual with an immigrant drawn from the metacommunity.

The metacommunity is changing on a much larger timescale and is assumed to be fixed during the evolution of the local community. The resulting distribution of species in the local community and expected values depend on four parameters, $$J$$, $$J_M$$, $$\theta$$ and $$m$$ (or $$I$$) and are derived by Etienne and Alonso (2005), including several simplifying limit cases like the one presented in the previous section (there called $$\langle\phi_n\rangle$$). The parameter $$m$$ is a dispersal parameter. If $$m=1$$ then the local community is just a sample from the metacommunity. For $$m=0$$ the local community is completely isolated from the metacommunity and all species will go extinct except one. This case has been analyzed by Hubbell himself. The case $$0<m<1$$ is characterized by a unimodal species distribution in a Preston Diagram and often fitted by a log-normal distribution. This is understood as an intermediate state between domination of the most common species and a sampling from the metacommunity, where singleton species are most abundant. UNTB thus predicts that in dispersal limited communities rare species become even rarer. The log-normal distribution describes the maximum and the abundance of common species very well but underestimates the number of very rare species considerably which becomes only apparent for very large sample sizes.

Species-area relationships
The Unified Theory unifies biodiversity, as measured by species-abundance curves, with biogeography, as measured by species-area curves. Species-area relationships show the rate at which species diversity increases with area. The topic is of great interest to conservation biologists in the design of reserves, as it is often desired to harbour as many species as possible.

The most commonly encountered relationship is the power law given by

S=cA^z$$

where S is the number of species found, A is the area sampled, and c and z are constants. This relationship, with different constants, has been found to fit a wide range of empirical data.

From the perspective of Unified Theory, it is convenient to consider S as a function of total community size J. Then $$S=kJ^z$$ for some constant k, and if this relationship were exactly true, the species area line would be straight on log scales. It is typically found that the curve is not straight, but the slope changes from being steep at small areas, shallower at intermediate areas, and steep at the largest areas.

The formula for species composition may be used to calculate the expected number of species present in a community under the assumptions of the Unified Theory. In symbols

E\left\{S|\theta,J\right\}= \frac{\theta}{\theta }+ \frac{\theta}{\theta+1}+ \frac{\theta}{\theta+2}+ \cdots + \frac{\theta}{\theta+J-1} $$

where θ is the fundamental biodiversity number. This formula specifies the expected number of species sampled in a community of size J. The last term, $$\theta/(\theta+J-1)$$, is the expected number of new species encountered when adding one new individual to the community. This is an increasing function of θ and a decreasing function of J, as expected.

By making the substitution $$J=\rho A$$ (see section on saturation above), then the expected number of species becomes $$\Sigma\theta/(\theta+\rho A-1)$$.

The formula above may be approximated to an integral giving

S(\theta)= 1+\theta\ln\left(1+\frac{J-1}{\theta}\right). $$

This formulation is predicated on a random placement of individuals.

Example
Consider the following (synthetic) dataset of 27 individuals:

a,a,a,a,a,a,a,a,a,a,b,b,b,b,c,c,c,c,d,d,d,d,e,f,g,h,i

There are thus 27 individuals of 9 species ("a" to "i") in the sample. Tabulating this would give:

a b  c  d  e  f  g  h  i 10  4  4  4  1  1  1  1  1

indicating that species "a" is the most abundant with 10 individuals and species "e" to "i" are singletons. Tabulating the table gives:

species abundance   1    2    3    4    5    6    7    8    9    10 number of species   5    0    0    3    0    0    0    0    0     1

On the second row, the 5 in the first column means that five species, species "e" through "i", have abundance one. The following two zeros in columns 2 and 3 mean that zero species have abundance 2 or 3. The 3 in column 4 means that three species, species "b", "c", and "d", have abundance four. The final 1 in column 10 means that one species, species "a", has abundance 10.

This type of dataset is typical in biodiversity studies. Observe how more than half the biodiversity (as measured by species count) is due to singletons.

For real datasets, the species abundances are binned into logarithmic categories, usually using base 2, which gives bins of abundance 0–1, abundance 1–2, abundance 2–4, abundance 4–8, etc. Such abundance classes are called octaves; early developers of this concept included F. W. Preston and histograms showing number of species as a function of abundance octave are known as Preston diagrams.

These bins are not mutually exclusive: a species with abundance 4, for example, could be considered as lying in the 2-4 abundance class or the 4-8 abundance class. Species with an abundance of an exact power of 2 (i.e. 2,4,8,16, etc.) are conventionally considered as having 50% membership in the lower abundance class 50% membership in the upper class. Such species are thus considered to be evenly split between the two adjacent classes (apart from singletons which are classified into the rarest category). Thus in the example above, the Preston abundances would be

abundance class 1   1-2   2-4   4-8  8-16 species        5     0    1.5   1.5   1

The three species of abundance four thus appear, 1.5 in abundance class 2–4, and 1.5 in 4–8.

The above method of analysis cannot account for species that are unsampled: that is, species sufficiently rare to have been recorded zero times. Preston diagrams are thus truncated at zero abundance. Preston called this the veil line and noted that the cutoff point would move as more individuals are sampled.

Dynamics
All biodiversity patterns previously described are related to time-independent quantities. For biodiversity evolution and species preservation, it is crucial to compare the dynamics of ecosystems with models (Leigh, 2007). An easily accessible index of the underlying evolution is the so-called species turnover distribution (STD), defined as the probability P(r,t) that the population of any species has varied by a fraction r after a given time t.

A neutral model that can analytically predict both the relative species abundance (RSA) at steady-state and the STD at time t has been presented in Azaele et al. (2006). Within this framework the population of any species is represented by a continuous (random) variable x, whose evolution is governed by the following Langevin equation:

\dot{x}=b-x/\tau+\sqrt{Dx}\xi(t) $$ where b is the immigration rate from a large regional community, $$-x/\tau$$ represents competition for finite resources and D is related to demographic stochasticity; $$\xi(t)$$ is a Gaussian white noise. The model can also be derived as a continuous approximation of a master equation, where birth and death rates are independent of species, and predicts that at steady-state the RSA is simply a gamma distribution.

From the exact time-dependent solution of the previous equation, one can exactly calculate the STD at time t under stationary conditions:

P(r,t)=A\frac{\lambda+1}{\lambda}\frac{(e^{t/\tau})^{b/2D}}{1-e^{-t/\tau}}\left(\frac{\sinh(\frac{t}{2\tau})}{\lambda}\right)^{\frac{b}{D}+1}\left(\frac{4\lambda^2}{(\lambda+1)^2e^{t/\tau}-4\lambda}\right)^{\frac{b}{D}+\frac{1}{2}}. $$ This formula provides good fits of data collected in the Barro Colorado tropical forest from 1990 to 2000. From the best fit one can estimate $$\tau$$ ~ 3500 years with a broad uncertainty due to the relative short time interval of the sample. This parameter can be interpreted as the relaxation time of the system, i.e. the time the system needs to recover from a perturbation of species distribution. In the same framework, the estimated mean species lifetime is very close to the fitted temporal scale $$\tau$$. This suggests that the neutral assumption could correspond to a scenario in which species originate and become extinct on the same timescales of fluctuations of the whole ecosystem.

Testing
The theory has provoked much controversy as it "abandons" the role of ecology when modelling ecosystems. The theory has been criticized as it requires an equilibrium, yet climatic and geographical conditions are thought to change too frequently for this to be attained. Tests on bird and tree abundance data demonstrate that the theory is usually a poorer match to the data than alternative null hypotheses that use fewer parameters (a log-normal model with two tunable parameters, compared to the neutral theory's three ), and are thus more parsimonious. The theory also fails to describe coral reef communities, studied by Dornelas et al., and is a poor fit to data in intertidal communities. It also fails to explain why families of tropical trees have statistically highly correlated numbers of species in phylogenetically unrelated and geographically distant forest plots in Central and South America, Africa, and South East Asia.

While the theory has been heralded as a valuable tool for palaeontologists, little work has so far been done to test the theory against the fossil record.

title: Unified neutral theory of biodiversity