The Monongahela River —often referred to locally as the Mon —is a 130-mile-long river on the Allegheny Plateau in north-central West Virginia and southwestern Pennsylvania. The river flows from the confluence of its west and east forks in north-central West Virginia northeasterly into southwestern Pennsylvania, then northerly to Pittsburgh and its confluence with the Allegheny River to form the Ohio River. The river's entire length is navigable via a series of locks and dams.