River, east-central U.S. Rising in the Appalachian Mountains of West Virginia, it is about 287 mi (462 km) long.
It flows southeast through the District of Columbia into Chesapeake Bay . It is navigable by large vessels to Washington, D.C. , above which it descends in a series of rapids and falls, including Great Falls. Noted for its beauty, the Potomac is also rich in history. Mount Vernon , home of Chesapeake and Ohio Canal National Historical Park parallels the river.