The Blackwater National Wildlife Refuge was established in 1933 as a waterfowl sanctuary for birds migrating along the critical migration highway called the Atlantic Flyway. The Refuge is located on Maryland's Eastern Shore, just 12 miles south of Cambridge, Maryland in Dorchester County, and consists of over 27,000 acres (110 km²) of freshwater impoundments, brackish tidal wetlands, open fields, and mixed evergreen and deciduous forests. Blackwater NWR is one of over 540 units in the National Wildlife Refuge System, which is managed by the United States Fish and Wildlife Service.

Blackwater Refuge is fed by the Blackwater River and the Little Blackwater River. The name "blackwater" comes from the tea-colored waters of the local rivers, which are darkened by the tannin that is picked up as the water drains through peat soil in the marshes.