The Potomac River forms part of the borders between Maryland and Washington, D.C. on the left descending bank and West Virginia and Virginia on the river's right descending bank. The majority of the lower Potomac River is part of the State of Maryland.

The Potomac River is approximately 405 miles long.  It is the fourth largest river along the Atlantic coast and the 21st largest in the United States.

Since the 1800's the U.S. Navy has been using its 2,000 acres reservation on the Potomac for munitions research and testing.

Despite the Navy's testing of explosives, the Potomac River and Mattawoman Creek have been untouched at Indian Head. Wooded areas and wetlands along the Potomac and Mattawoman Creek are home to populations of birds, animals, and trees. Several bald eagle nests have been reported near an Indian Head explosion range.

Fun Facts

• The Potomac River is situated in an area rich in American history which has led to the River's nickname, "The Nation's River".
• During the Civil War, the Potomac River divided the Union from the Confederacy.  It also gave name to the Union's largest army, the Army of the Potomac.
• In 1864, Washington, D.C. began using the Potomac River as its principal source of drinking water when the Washington Aqueduct was opened.
• The Potomac's common spelling through the 18th century was "Patowmack." An earlier spelling was "Patawomeke." The spelling of the name was simplified over the years to "Potomac".
• The Potomac River flows into the Chesapeake Bay and affects more than 6 million people who live within the Potomac watershed, the land area where water drains towards the mouth of the river.