The District of Columbia is that portion of the territory of the United States ceded by the State of Maryland for the permanent seat of government of the United States, including the river Potomac in its course through the District, and the islands therein.
D.C. Code § 1-101
Organic Act of 1878: See Acts Relating to the Establishment of the District of Columbia and its Various Forms of Governmental Organization in Volume 1.
Boundary line between District of Columbia and Commonwealth of Virginia established: See Acts Relating to the Establishment of the District of Columbia and its Various Forms of Governmental Organization in Volume 1.
"District" defined, see § 2-2601. Metropolitan Police District, creation, see § 5-101.01. National capital service area, see § 1-207.39. .