The Chesapeake Bay is the largest estuary in the United States. It lies off the Atlantic Ocean, surrounded by Maryland and Virginia. The Chesapeake Bay's watershed covers 64299 square miles (166534 km2 ) in the District of Columbia and parts of six states: New York, Pennsylvania, Delaware, Maryland, Virginia, and West Virginia. More than 150 rivers and streams drain into the Bay. The Chesapeake Bay is approximately 200 miles (300 km) long, from the Susquehanna River in the north to the Atlantic Ocean in the south. At its narrowest point between Kent County's Plum Point (near Newtown) and the Harford County shore near Romney Creek, the Bay is 2.8 miles (4.5 km) wide; at its widest point, just south of the mouth of the Potomac River, it is 30 miles (50 km) wide.