District of Columbia (D.C.)

The District of Columbia was created as a 10-mile square from portions of Maryland and Virginia in 1791. In 1801, the part from Virginia became Alexandria County and the part from Maryland became Washington County. In 1846, the portion of the District west of the Potomac River was retroceded to the state of Virginia.

  • 1800 federal census extant for the Maryland side and lost for the Virginia side.
  • 1810 federal census lost for the whole district.
  • 1820—1940 federal censuses extant for whole district except for 1890.