The Chesapeake Bay (// CHESS-ə-peek) is the largest estuary in the United States. The Bay is located in the Mid-Atlantic region and is primarily separated from the Atlantic Ocean by the Delmarva Peninsula (including the parts: the Eastern Shore of Maryland / Eastern Shore of Virginia and the state of Delaware) with its mouth of the Bay at the south end located between Cape Henry and Cape Charles. With its northern portion in Maryland and the southern part in Virginia, the Chesapeake Bay is a very important feature for the ecology and economy of those two states, as well as others surrounding within its watershed. More than 150 major rivers and streams flow into the Bay's 64,299-square-mile (166,534 km2) drainage basin, which covers parts of six states (New York, Pennsylvania, Delaware, Maryland, Virginia and West Virginia) and all of District of Columbia.
|Etymology||Chesepiooc, Algonquian for village "at a big river"|
|Primary inflows||Susquehanna River mouth|
east of Havre de Grace, Maryland
|River sources||Deer Creek,|
James River, Chester River, Choptank River, Nanticoke River, Pocomoke River
|Primary outflows||Atlantic Ocean|
north of Virginia Beach, Virginia
|Catchment area||64,299 sq mi (166,530 km2)|
|Basin countries||United States|
|Max. length||200 mi (320 km)|
|Max. width||30 mi (48 km)|
|Surface area||4,479 sq mi (11,600 km2)|
|Average depth||21 ft (6.4 m)|
|Residence time||180 days|
|Settlements||Annapolis, Baltimore, Cambridge, Cape Charles, Chesapeake, Chesapeake Beach, Elkton, Hampton, Havre de Grace, Newport News, Norfolk, Portsmouth, Virginia Beach|
|Official name||Chesapeake Bay Estuarine Complex|
|Designated||4 June 1987|
The Bay is approximately 200 miles (320 km) long from its northern headwaters in the Susquehanna River to its outlet in the Atlantic Ocean. It is 2.8 miles (4.5 km) wide at its narrowest (between Kent County's Plum Point near Newtown in the east and the Harford County western shore near Romney Creek) and 30 miles (48 km) at its widest (just south of the mouth of the Potomac River which divides Maryland from Virginia). Total shoreline including tributaries is 11,684 miles (18,804 km), circumnavigating a surface area of 4,479 square miles (11,601 km2). Average depth is 21 feet (6.4 m), reaching a maximum of 174 feet (53 m). The Bay is spanned twice, in Maryland by the Chesapeake Bay Bridge from Sandy Point (near Annapolis) to Kent Island and in Virginia by the Chesapeake Bay Bridge–Tunnel connecting Virginia Beach to Cape Charles.
Known for both its beauty and bounty, the Bay has become "emptier", with fewer crabs, oysters and watermen (fishermen) since the mid-20th century. Nutrient pollution and urban runoff have been identified as major components of impaired water quality in the bay stressing ecosystems and compounding the decline of shellfish due to overharvesting. Restoration efforts that began in the 1990s have continued into the 21st century and show potential for growth of the native oyster population. The health of the Chesapeake Bay improved in 2015, marking three years of gains over a four-year period, according to a 2016 report by the University of Maryland. The bay is experiencing other environmental concerns, including climate change which is causing sea level rise that erodes coastal areas and infrastructure and changes to the marine ecosystem. These changes have already changed the coastline eroding islands like Holland Island or Long Island and threatening local infrastructure and economies.