Beaver River is a tributary of the Ohio River in Western Pennsylvania. Approximately 21 mi (34 km) long, it flows through a historically important coal-producing region north of Pittsburgh. The river is formed in Lawrence County by the confluence of the Mahoning and Shenango rivers in the Mahoningtown neighborhood of New Castle. It flows generally south, past West Pittsburg and Homewood, then receives Connoquenessing Creek west of Ellwood City and flows past Beaver Falls and New Brighton. It joins the Ohio at Bridgewater and Rochester at the downstream end of a sharp bend in the Ohio approximately 20 mi (32 km) northwest of Pittsburgh. In the lower reaches near the Ohio River, the Beaver cuts through a gorge of underlying sandstone. The river is roughly parallel to the border with the state of Ohio, with both Interstate 376 and Pennsylvania Route 18 running parallel to the river itself.