The Potomac River is 285 miles long. It flows mostly southeast to Chesapeake Bay, forming part of the boundary between Maryland and West Virginia, then separating Virginia from both Maryland and the District of Columbia. It is navigable for large ships to Washington, D.C. Its primary tributary is the Shenandoah River, which joins it at Harpers Ferry.
The river is noted for both its beauty and its historical associations. The Potomac River served as a principal theater for the Civil War, once linking the diverse region, then becoming a geographic division between North and South.
Later, industrialization degraded the health of the river, and the regional population began to search for ways to stop the damage and improve the quality of the river.
The last fifty years has seen increased citizen involvement in promoting restoration and repair. However, urban growth and suburbanization have placed new and different stresses on the river.