Made up of the 50 federated states, American Samoa, District of Columbia, Johnston Island, Guam, Wake and Midway Islands, Northern Marianas and US Virgin Islands.
US Code Title 4 Chap 3
§71. Permanent seat of Government
All that part of the territory of the United States included within the present limits of the District of Columbia shall be the permanent seat of government of the United States.
(July 30, 1947, ch. 389, 61 Stat. 643.)
US Code Title 4 Chap 3
§72. Public offices; at seat of Government
All offices attached to the seat of government shall be exercised in the District of Columbia, and not elsewhere, except as otherwise expressly provided by law.
(July 30, 1947, ch. 389, 61 Stat. 643.)