By the constitutional provision referred to in the preceding section, Congress is authorized also to exercise exclusive legislation "over all places purchased by the consent of the legislature of the state in which the same shall be for the erection of forts, magazines, arsenals, dock yards, and other needful buildings." Territory ceded to the United States under this provision ceases to be territory of the state, and is no longer subject to the jurisdiction of the state by which it is thus ceded. The grant to the United States of the exclusive power of legislation with reference to such territory excludes it and the persons permanently residing therein from the jurisdiction of the state, and as a consequence no state can tax property which is thus situated, nor punish crimes committed within such territory; for the persons therein permanently residing are not citizens of any state. It has been held, however (Ft. Leavenworth Railroad Co. v. Lowe), that in ceding such territory the state may reserve the power to tax property located there, and also the right to serve process of its courts on persons found therein. Such a reservation of power has been recognized by the United States as proper, and it is expedient, for otherwise the forts, navy-yards, and public buildings of the United States might be resorted to by those seeking to evade the state laws.

It is to be borne in mind that it is only with reference to territory thus voluntarily ceded that the state loses its jurisdiction. The United States may, like any other sovereign power, acquire the ownership of property by purchase, or by the exercise of the power of eminent domain (Kohl v. United States). But it acquires exclusive jurisdiction over property thus purchased or condemned only by voluntary cession from the state. For instance, if at the time of the admission of a state to the Union, the United States has forts or public buildings located within the limits of such state as admitted, the state acquires jurisdiction with reference thereto unless in the act of admission or by subsequent voluntary action of the state exclusive jurisdiction is reserved or ceded to the United States. As has already been indicated in the chapter in which the power of the United States to punish crimes is considered (see above, § 56), Congress has legislated for the punishment of crimes committed in the District of Columbia and in other ceded districts, and like legislative power with reference to such districts may be and is exercised by Congress in other matters.