The Real Constitution: Article IV, Section III (Addition of New States; Governance of US Territories)

New States may be admitted by the Congress into this Union; but no new State shall be formed or erected within the Jurisdiction of any other State; nor any State be formed by the Junction of two or more States, or Parts of States, without the Consent of the Legislatures of the States concerned as well as of the Congress.


The Congress shall have Power to dispose of and make all needful Rules and Regulations respecting the Territory or other Property belonging to the United States; and nothing in this Constitution shall be so construed as to Prejudice any Claims of the United States, or of any particular State.

The Articles of Confederation allowed Canada to join the Union just by asking and allowed any other state to join with the consent of nine states. Edmund Randolph's Virginia Plan allowed for "admission of States lawfully arising within the limits of the United States...with the consent of a number of voices in the National legislature less than the whole."