Located in the South Atlantic region of the US, the District of Columbia has a total area of 69 sq mi (179 sq km), of which land takes up 63 sq mi (163 sq km) and inland water 6 sq mi (16 sq km). The District is bounded on the N, E, and S by Maryland, and on the W by the Virginia shore of the Potomac River. The total boundary length is 37 mi (60 km).
For statistical purposes, the District of Columbia (coextensive since 1890 with the city of Washington, D.C.) is considered part of the Washington, D.C., metropolitan area, which since 1985 has embraced Calvert, Charles, Frederick, Montgomery, and Prince George's counties in Maryland, and Arlington, Fairfax, Loudoun, Prince William, and Stafford counties in Virginia, along with a number of other Virginia jurisdictions, most notably the city of Alexandria.