The Potomac River watershed drains approximately 14,670 square miles of land, covering four states. Major bodies of water in the area include the Potomac, Anacostia, Cacapon, Monocacy, the North Branch, the South Branch, the Occoquan, and the Shenandoah Rivers. The Potomac River flows over 383 miles from Fairfax Stone, West Virginia to Point Lookout, Maryland. Major cities in the watershed include Washington, D.C, Bethesda, Cumberland, Frederick, Gettysburg and Alexandria. Forest is the major land use, followed by agriculture. The 2000 census population of the watershed was approximately 5.35 million. Washington, D.C. alone had 3.7 million people (2000 census). Based on information available at the Interstate Commission on the Potomac River Basin website.