Allegheny(redirected from Alleghany)
Also found in: Dictionary, Thesaurus.
Allegheny(ăl`əgā'nē, ăl`əgä'nē), river, 325 mi (523 km) long, rising in N central Pa., and flowing NW into N.Y., then SW through Pa. to the MonongahelaMonongahela
, river, 128 mi (206 km) long, formed at Fairmont, N W.Va., by the junction of the West Fork and Tygart rivers. It flows north, through a valley marked by a decline in heavy industry and coal mining, into SW Pennsylvania, where it joins the Allegheny to form the Ohio
..... Click the link for more information. , with which it forms the OhioOhio,
river, 981 mi (1,579 km) long, formed by the confluence of the Allegheny and Monongahela rivers in SW Pa., at Pittsburgh; it flows northwest, then generally southwest to enter the Mississippi River at Cairo, Ill.
..... Click the link for more information. River at Pittsburgh; drains 11,580 sq mi (29,992 sq km). Before the railroad era, the river was an important commercial route and is still used to transport coal and other bulky freight. Kinzua Dam (completed in 1965), a federal flood-control project on the river, forms a large lake; there are also dams on the river's tributaries. The Allegheny's basin has coal, oil, and natural gas.