Potomac River with Key Bridge above and Georgetown University, Washington DC, USA - stock photo

The Potomac River is located along the mid-Atlantic Ocean coast of the United States and flows into the Chesapeake Bay. The river (main stem and North Branch) is approximately 405 miles (652 km) long, with a drainage area of about 14,700 square miles. In terms of area, this makes the Potomac River the fourth largest river along the Atlantic coast of the United States and the 21st largest in the United States. Over 5 million people live within the Potomac watershed.