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 mi (19 km) south of Cambridge, Maryland in Dorchester County, and consists of over 28,000 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.In addition to a wealth of wetlands and forests, Blackwater Refuge is also host to over 250 bird species, 35 species of reptiles and amphibians, 165 species of threatened and endangered plants, and numerous mammals that can be spotted throughout the year in Blackwater's marshes, forests, meadows, and fields.