Congress is given power "To exercise exclusive legislation in all cases whatsoever over such district (not exceeding ten miles square) as may by cession of particular states and the acceptance of Congress become the seat of government of the United States" (Art. I, § 8, ¶ 17). In pursuance of this provision and under the authority of Congress, Maryland and Virginia in 1790 ceded to the United States portions of their territory which were set apart as the seat of the federal government. Subsequently the portion of the district which had been ceded by Virginia was re-ceded to that state, and the district now comprises only the territory acquired from Maryland. Within this district the exclusive power of legislation for all purposes is in Congress, and although Congress in 18 71 undertook to establish a government for the district with legislative powers, and the government thus established continued in operation until 1874, it was seriously questioned whether the legislation enacted by it was valid. Indeed, in the case of Roach v. Van Riswick, decided by the Supreme Court of the District of Columbia in 1879, the conclusion was reached that all the legislation of the government thus established was without legal authority.

However, it is well settled that Congress may create municipal corporations within territory which is subject to its exclusive jurisdiction, and by the legislation of Congress now in force on the subject, the District is a public corporation, having such authority as is usually conferred upon such corporations (Metropolitan Railroad Co. v. District of Columbia'). The District is not a state of the Union, and those who permanently reside within it are not citizens of any state, although they are citizens of the United States (Hepburn v. Ellzey).