|- location||Allegany Township, Potter County, near Coudersport, Pennsylvania at the corner of Ben Green and Cobb Hill Rd|
|- elevation||~2,490 feet (760 m)|
|Ohio River at Pittsburgh, Pennsylvania|
ALLEGHENY RIVER Latitude and Longitude:
|Length||325 miles (523 km)|
|Basin size||11,580 square miles (30,000 km2)|
|- average||19,750 cu ft/s (559 m3/s) at the village of Natrona, PA (river mile 24.3) |
|- left||Tionesta Creek, Clarion River, Redbank Creek, Mahoning Creek, Crooked Creek, Kiskiminetas River, Buffalo Creek, Chartiers Run, Pucketa Creek|
|- right||Conewango Creek, Brokenstraw Creek, Oil Creek, French Creek, Bull Creek, Deer Creek, Squaw Run, Pine Creek, Girtys Run|
|Designated||April 20, 1992|
The Allegheny River ( // AL-ə-GAY-nee) is a principal tributary of the Ohio River; it is located in the Eastern United States. The Allegheny River joins with the Monongahela River to form the Ohio River at the "Point" of Point State Park in Downtown Pittsburgh, Pennsylvania. The Allegheny River is, by volume, the main headstream of both the Ohio and Mississippi Rivers.
The river is approximately 325 miles (523 km) long, running through the U.S. states of New York and Pennsylvania.  It drains a rural dissected plateau of 11,580 square miles (30,000 km2) in the northern Allegheny Plateau, providing the northeastern most drainage in the watershed of the Mississippi River. Its tributaries reach to within 8 miles (13 km) of Lake Erie in southwestern New York.
The name Allegheny probably comes from Lenape welhik hane   or oolikhanna, which means 'best flowing river of the hills' or 'beautiful stream'.  There is a Lenape legend of a tribe called "Allegewi" who used to live along the river. 
The following account of the origin of the name Allegheny was given in 1780 by Moravian missionary David Zeisberger: "All this land and region, stretching as far as the creeks and waters that flow into the Alleghene the Delawares called Alligewinenk, which means 'a land into which they came from distant parts'. The river itself, however, is called Alligewi Sipo. The whites have made Alleghene out of this, the Six Nations calling the river the Ohio." 
Indians, including the Lenni Lenape and Iroquois, considered the Allegheny and Ohio rivers as the same, as is suggested by a New York State road sign on Interstate 86 that refers to the Allegheny River also as Ohiːyo'.  The Geographic Names Information System lists O-hee-yo and O-hi-o as variant names.  The river is called Ohi:'i:o` (river beautiful) in the Seneca language.  In New York, areas around the river are often named with the alternate spelling Allegany in reference to the river; for example, the Village of Allegany and Allegany State Park. Port Allegany, located along the river in Pennsylvania near the border with New York, also follows this pattern.
The Allegheny River rises in north central Pennsylvania, on Cobb Hill in central Potter County, approximately 10 miles (16 km) south of the New York border. It flows west past Coudersport then turns north at Port Allegany and proceeds into western New York, looping westward across southern Cattaraugus County for approximately 30 miles (48 km), past Portville, Olean, St. Bonaventure University and Salamanca and flowing through Seneca Indian Nation lands close to the northern boundary of Allegany State Park before re-entering northwestern Pennsylvania approximately 20 miles (32 km) southeast of Jamestown, New York.
It flows in a broad zigzag course generally southward across Western Pennsylvania; first flowing southwest past Warren, Tidioute, Tionesta, Oil City, and Franklin, forming much of the northwestern boundary of Allegheny National Forest. South of Franklin it turns southeast across Clarion County in a meandering course, then turns again southwest across Armstrong County, flowing past Kittanning, Ford City, Clinton, and Freeport.
The river enters both Allegheny and Westmoreland counties, the Pittsburgh suburbs, and the City of Pittsburgh from the northeast. It passes Sligo, Karns, and Natrona in Harrison Township; Metcalf, Braeburn, Lower Burrell, and New Kensington; Brackenridge, Tarentum, Creighton, Clyde, Springdale, Harmarville, Plum Borough, Oakmont, Verona, PennHills, Blawnox, O'hara Township, Aspinwall, Sharpsburg, Etna, Millvale, Lawrenceville, Highland Park, the North Side, Downtown Pittsburgh, and Point State Park. The Allegheny joins with the Monongahela River at the "Point" in Downtown Pittsburgh, Pennsylvania to form the Ohio River.
In its upper reaches, the Allegheny River is joined from the south by Potato Creek 1.7 miles (2.7 km) downstream of Coryville, Pennsylvania and from the north by Olean Creek at Olean, New York. Tunungwant "Tuna" Creek joins the river from the south in Carrollton, New York (flowing north from Bradford, Pennsylvania); the Great Valley Creek and Little Valley Creek join the river from the north at Salamanca, New York before becoming the Allegheny Reservoir.
After re-entering Pennsylvania, the river is joined from the east by Kinzua Creek 10 miles (16 km) upstream of Warren; from the north by Conewango Creek at Warren; from the west by Brokenstraw Creek; from the east by East Hickory Creek at East Hickory; from the east by Tionesta Creek at Tionesta; from the north by Oil Creek at Oil City; from the west by French Creek at Franklin; from the east by the Clarion River, a principal tributary, at Parker; from the east by Crooked Creek southeast of Kittanning; and from the east by the Kiskiminetas River, another principal tributary, at Schenley. Buffalo Creek enters at Freeport, Chartiers Run enters at Lower Burrell, Bull Creek enters at Tarentum, Pucketa Creek enters near New Kensington, Riddle Run enters at Springdale, and Girtys Run enters at Millvale. Many additional streams enter or join with the Allegheny River along its course.
The course of the Allegheny River traverses the following 75 political subdivisions, listed in order of first encounter going downstream.
- Allegany Township, Potter County
- Eulalia Township, Potter County
- Coudersport, Pennsylvania
- Roulette Township, Potter County
- Liberty Township, McKean County
- Port Allegany, Pennsylvania
- Annin Township, McKean County
- Eldred Township, McKean County
- Eldred, Pennsylvania
- Portville, New York
- Olean, New York
- Allegany, New York
- Salamanca, New York
- South Valley, New York
- Elk Township, Warren County
- Mead Township, Warren County
- Glade Township, Warren County
- Warren, Pennsylvania
- Pleasant Township, Warren County
- Conewango Township, Warren County
- Brokenstraw Township, Warren County
- Watson Township, Warren County
- Deerfield Township, Warren County
- Limestone Township, Warren County
- Tidioute, Pennsylvania
- Triumph Township, Warren County
- Hickory Township, Forest County
- Harmony Township, Forest County
- Tionesta Township, Forest County
- Tionesta, Pennsylvania
- President Township, Venango County
- Cranberry Township, Venango County
- Cornplanter Township, Venango County
- Oil City, Pennsylvania
- Sugarcreek, Pennsylvania
- Sandycreek Township, Venango County
- Rockland Township, Venango County
- Victory Township, Venango County
- Clinton Township, Venango County
- Scrubgrass Township, Venango County
- Richland Township, Clarion County
- Allegheny Township, Butler County
- Foxburg, Pennsylvania
- Perry Township, Clarion County
- Hovey Township, Armstrong County
- Toby Township, Clarion County
- Madison Township, Clarion County
- Bradys Bend Township, Armstrong County
- Washington Township, Armstrong County
- Madison Township, Armstrong County
- Pine Township, Armstrong County
- Boggs Township, Armstrong County
- Rayburn Township, Armstrong County
- East Franklin Township, Armstrong County
- Kittanning, Pennsylvania
- Manor Township, Armstrong County
- Cadogan Township, Armstrong County
- Bethel Township, Armstrong County
- South Buffalo Township, Armstrong County
- Gilpin Township, Armstrong County
- Allegheny Township, Westmoreland County
- Freeport, Pennsylvania
- Harrison Township, Allegheny County
- Lower Burrell, Pennsylvania
- Tarentum, Pennsylvania
- East Deer Township, Allegheny County
- Plum, Pennsylvania
- Springdale, Pennsylvania
- Harmar Township, Allegheny County
- Verona, Pennsylvania
- O'Hara Township, Allegheny County
- Penn Hills Township, Allegheny County
- Pittsburgh, Pennsylvania
- Etna, Pennsylvania
- Millvale, Pennsylvania
- Allegheny River Lock and Dam No. 2
- Allegheny River Lock and Dam No. 3
- Allegheny River Lock and Dam No. 4
- Allegheny River Lock and Dam No. 5
- Allegheny River Lock and Dam No. 6
- Allegheny River Lock and Dam No. 7
- Allegheny River Lock and Dam No. 8
- Allegheny River Lock and Dam No. 9
In the 16th century, control of the river valley passed back-and-forth between Algonquian-speaking Shawnee and the Iroquois. By the time of the arrival of the French in the early 18th century, the Shawnee were once again in control and formed an alliance with the French against the incursion of British settlement across the Allegheny Mountains. The conflict over the expansion of British settlement into the Allegheny Valley and the surrounding Ohio Country was a primary cause of the French and Indian War in the 1750s.  During the war, the village of Kittanning – the principal Shawnee settlement on the river – was completely destroyed by British reprisal raids from Central Pennsylvania.
Nevertheless, the British, after gaining control of the area in the 1763 Treaty of Paris, kept the area closed to white settlement, in part to repair and maintain relations with the Native Americans. The pressure to open the river valley and the surrounding area to settlement is considered by historians to be one of the root causes of the American Revolutionary War in the following decade. After the war, the entire river valley became part of the United States of America.
During the 19th century, the river became a principal means of navigation in the upper Ohio valley, especially for the transport of coal. Although the building of the railroads lessened the importance of the river somewhat, the lower river (navigable as far as East Brady, Pennsylvania through locks) has continued to serve as route of commercial transportation until the present day. In 1859, the first U.S. petroleum was drilled north of the river at Titusville.
One of the underlying premises of the Genesee Valley Canal was its connection to the river, opening a trade route from Rochester, New York to the west. The advent of the railroads destroyed any interest that Pennsylvania might have had in participating by improving navigation on the river.
In 1965, the completion of the federally sponsored Kinzua Dam for flood-control in northwestern Pennsylvania east of Warren created the long Allegheny Reservoir, part of which is included in the Allegheny National Recreation Area. The dam flooded parts of lands deeded "forever" to the Seneca Nation of Indians by the 1794 Treaty of Canandaigua, and to lands given to Cornplanter and his descendants. The event was described in the Johnny Cash song "As Long as the Grass Shall Grow" from the 1964 album Bitter Tears: Ballads of the American Indian, which focused on the history of and problems facing Native Americans in the United States.
The construction of the dam and the filling of the Allegheny Reservoir also necessitated the elimination of the small village of Corydon, which was located at the confluence of Willow Creek with the Allegheny River; and the small village of Kinzua, which was located at the confluence of Kinzua Creek with the Allegheny River. All residents of both villages were forced to move.
Many prominent individuals opposed the construction of the dam at that time because of the damage it would do to Seneca lands, including Pennsylvania Congressman John P. Saylor of Johnstown, and Howard Zahniser, executive director of The Wilderness Society and native of Tionesta—a small settlement located along the Allegheny River several miles downstream from Warren. During the campaign for the 1960 United States presidential election, John F. Kennedy assured the Seneca Nation that he would oppose the dam if elected. However, he failed to follow through on his pledge upon becoming president.
In 2008, Katie Spotz became the first person to swim the entire 325 miles (523 km) of the Allegheny River; she was accompanied by safety kayaker, James Hendershott.  The team began at the river's source in Raymond, Pennsylvania on July 22 and finished at the "Point" in Downtown Pittsburgh on August 21. 
In 2017, Rye Development received a licence from the Federal Energy Regulatory Commission to construct a hydroelectric plant to replace the Highland Park dam. Construction of the 17-megawatt plant was set to begin in 2018. 
- East Brady
- East Hickory
- Ford City
- Lower Burrell
- New Kensington
- Oil City
- Penn Hills
- Port Allegany
- West Hickory
- West Kittanning
- Woodland Heights
- Allegheny Islands State Park
- Allegheny Riverfront Park
- List of rivers of New York
- List of rivers of Pennsylvania
- Pittsburgh Flood of 1936
- Pittsburgh Three Rivers Regatta
- USGS Data Report 2009 Retrieved June 16, 2018.
- "Allegheny River". Geographic Names Information System. United States Geological Survey. Retrieved 2010-05-13.
- "welhik". Lenape Talking Dictionary. Archived from the original on October 4, 2011. Retrieved December 14, 2011.
- "Heckewelder here does not give the strict meaning of hanne. The word in common use among Algonkin [i.e., Algonquian] tribes for river is sipu, and this includes the idea of 'a stream of flowing water'. But in the mountainous parts of Pennsylvania, Maryland, and Virginia sipu did not sufficiently convey the idea of a rapid stream, roaring down mountain gorges, and hanne takes its place to designate not a mere sipu, or flowing river, but a rapid mountain stream." Russell, Erret (1885). "Indian Geographical Names". Magazine of Western History. 2 (1): 53–59.
- Alleghany, or as some prefer to write it, Allegheny,—the Algonkin name of the Ohio River, but now restricted to one of its branches,—is probably (Delaware) welhik-hanné or [oo]lik-hanné, 'the best (or, the fairest) river.' Welhik (as Zeisberger wrote it) is the inanimate form of the adjectival, meaning 'best,' 'most beautiful.' In his Vocabulary, Zeisberger gave this synthesis, with slight change of orthography, as "Wulach'neü" [or [oo]lakhanne[oo], as Eliot would have written it,] with the free translation, "a fine River, without Falls." The name was indeed more likely to belong to rivers 'without falls' or other obstruction to the passage of canoes, but its literal meaning is, as its composition shows, "best rapid-stream," or "finest rapid-stream;" "La Belle Riviere" of the French, and the Oue-yo´ or O hee´ yo Gä-hun´-dä, "good river" or "the beautiful river," of the Senecas. For this translation of the name we have very respectable authority,—that of Christian Frederick Post, a Moravian of Pennsylvania, who lived seventeen years with the Muhhekan Indians and was twice married among them, and whose knowledge of the Indian languages enabled him to render important services to the colony, as a negotiator with the Delawares and Shawanese of the Ohio, in the French war. In his "Journal from Philadelphia to the Ohio" in 1758, after mention of the 'Alleghenny' river, he says: "The Ohio, as it is called by the Sennecas. Alleghenny is the name of the same river in the Delaware language. Both words signify the fine or fair river." La Metairie, the notary of La Salle's expedition, "calls the Ohio, the Olighinsipou, or Aleghin; evidently an Algonkin name,"—as Dr. Shea remarks. Heckewelder says that the Delawares "still call the Allegany (Ohio) river, Alligéwi Sipu,"—"the river of the Alligewi" as he chooses to translate it. In one form, we have wulik-hannésipu, 'best rapid-stream long-river;' in the other, wuliké-sipu, 'best long-river.' Heckewelder's derivation of the name, on the authority of a Delaware legend, from the mythic 'Alligewi' or 'Talligewi,'—"a race of Indians said to have once inhabited that country," who, after great battles fought in pre-historic times, were driven from it by the all-conquering Delawares,—is of no value, unless supported by other testimony. Trumbull, J. Hammond (1870). The Composition of Indian Geographical Names. Hartford, Conn. pp. 13–14.
- Stewart, George R. (1967). Names on the Land. Boston, Massachusetts: Houghton Mifflin Company. p. 8. ISBN 0-938530-02-X.
- Zeisberger, David (1999). David Zeisberger's History of the Northern American Indians in 18th Century Ohio, New York and Pennsylvania. Wennawoods Publishing. p. 33. ISBN 1-889037-17-6.
- "Glossary of Seneca Words". Internet Sacred Text Archive.
"Know the Rivers!" (PDF). fishandboat.com.
All dams on the Allegheny River are Fixed Crest
- MacCorkle, William Alexander. "The historical and other relations of Pittsburgh and the Virginias". Historic Pittsburgh General Text Collection. University of Pittsburgh. Retrieved 12 September 2013.
- Allegheny Wild and Scenic River – Allegheny National Forest. Retrieved June 16, 2018.
- Shuster, Patrick; Garrone, Francine (2008-08-18). "Ohio woman swimming length of Allegheny River". Pittsburgh Tribune-Review. Tribune-Review Publishing Company. Retrieved June 16, 2018.
- Nephin, Dan (August 22, 2008). "Ohio swimmer completes 325-mile swim of Allegheny". Pittsburgh Tribune-Review. Tribune-Review Publishing Company. Retrieved June 16, 2018.
- Panizzi, Tawnya (April 12, 2017). "Feds issue license for proposed hydroelectric plant for Highland Park Dam at Aspinwall". The Valley News Dispatch. Tribune-Review Publishing Company. Retrieved June 16, 2018.
- Schafer, Jim; Mike Sajna (1992). The Allegheny River: Watershed of the Nation. University Park, Pennsylvania, US: The Pennsylvania State University Press. ISBN 978-0-271-00836-3.
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