Allegheny << `al` uh GAY nee, >> River, is a major stream of western Pennsylvania and a principal headwater of the Ohio River. It rises in the hilly plateau country of north-central Pennsylvania, curves across the southwest corner of New York, and returns to Pennsylvania. The Allegheny then continues south to Pittsburgh, where it joins the Monongahela River to form the Ohio. The Allegheny is about 325 miles (523 kilometers) long, and drains about 11,400 square miles (29,530 square kilometers). Its branches include the Kiskiminetas, Clarion, and Conemaugh rivers and Red Bank, Oil, and French creeks. Major deposits of coal, oil, and natural gas lie in the drainage basin. The river is navigable with a channel for 70 miles (110 kilometers), from Pittsburgh to East Brady.
