The Potomac River is located along the mid-Atlanticcoast of the United States and flows into the ChesapeakeBay. The river (main stem and North Branch) isapproximately 405 miles (652 km) long, with a drainagearea of about 14,700 square miles (38,000 km²). The riverforms part of the borders between Maryland and Washington,D.C., on the left descending bank and WestVirginia and Virginia on the river's right descendingbank