District of Columbia
- Area: 68.3 sq mi
- Population (2000): 582,049
- Time Zone: Eastern
The District of Columbia comprises an area carved out from the state of Maryland on the north bank of the Potomac River where it is joined by the Anacostia River, across from Virginia. It is entirely occupied by the city of Washington, the capital of the United States. As originally envisaged, the district was to be a diamond-shaped are that extended southwards into Virginia, but that section of the district was retroceded a few years later and now largely forms Arlington, VA and part of Alexandria, VA.
The District of Columbia is not part of any state and is administered directly by Congress, although the city of Washington has had a mayor since the 1970s.