The Rappahannock River is a river in eastern Virginia in the Unite States, approximately 184 mi (294 km) in length. It traverses the entire northern part of the state, from the Blue Ridge Mountains in the west across the Piedmont to Chesapeake Bay south of the Potomac. It is considered by some[who?] to have been the boundary between the "North" (the Union) and the "South" (the Confederate States of America) during the Civil War, which are geographic regions still referenced today. An important river in U.S. history, it was the site of early settlements in the Virginia Colony and was later a major theater of battle in the American Civil War. It drains an area of 2,848 sq mi (7405 km²), approximately 6% of the state of Virginia. Much of the watershed is rural and forested but has seen growing development in recent decades with the southward expansion of the Virginia suburbs of Washington, D.C.