States by Order of Entry Into the Union

Updated February 28, 2017 | Infoplease Staff

The original 13 colonies were a group of British territories in North America. They were founded in the 17th and 18th centuries and became The Thirteen Colonies in 1776, when they declared independence. The colonies became states of the new nation in 1788, when New Hampshire became the ninth and final necessary state to ratify the United States Constitution. The date each state joined the Union is shown in the table below. Five states were added during the 20th century. Alaska and Hawaii were the last states to join the Union -- both in 1959.

Joining the Union

Article 4, Section 3 of the U.S. Constitution lays out how a new state can join the Union:

New States may be admitted by the Congress into this Union; but no new States 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.

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