Political divisions. Main articles: Political divisions of the United States, U.S

Main articles: Political divisions of the United States, U.S. state, Territories of the United States and List of states and territories of the United States

Further information: Territorial evolution of the United States and United States territorial acquisitions

The United States is a federal union of 50 states. The original 13 states were the successors of the 13 colonies that rebelled against British rule. Early in the country's history, three new states were organized on territory separated from the claims of the existing states: Kentucky from Virginia; Tennessee from North Carolina; and Maine from Massachusetts. Most of the other states have been carved from territories obtained through war or purchase by the U.S. government. One set of exceptions includes Vermont, Texas, and Hawaii: each was a well-established independent republic before joining the union. During the American Civil War, West Virginia broke away from Virginia. The most recent state—Hawaii—achieved statehood on August 21, 1959.^[268] The states do not have the right to unilaterally secede from the union.^[269]

The states compose the vast bulk of the U.S. land mass. The District of Columbia is a federal district which contains the capital of the United States, Washington, D.C. The United States also possesses five major overseas territories: Puerto Rico and the United States Virgin Islands in the Caribbean; and American Samoa, Guam, and the Northern Mariana Islands in the Pacific.^[270] Those born in the major territories are birthright U.S. citizensexcept Samoans. Samoans born in American Samoa are born U.S. nationals, and may become naturalized citizens.^[271] American citizens residing in the territories have fundamental constitutional protections and elective self-government, with a territorial Member of Congress, but they do not vote for president as states. Territories have personal and business tax regimes different from that of states.^[272]

The United States also observes tribal sovereignty of the Native Nations. Though reservations are within state borders, the reservation is a sovereign entity. While the United States recognizes this sovereignty, other countries may not.^[273]