Article IV, Section 3, Clause 1 of the Constitution grants to Congress the authority to admit new states into the Union. Since the establishment of the United States in 1776, the number of states has expanded from the original 13 to 50. Each new state has been admitted on an equal footing with the existing states.
The following table is a list of all 50 states and their respective dates of statehood. The first 13 became states in July 1776 upon agreeing to the Declaration of Independence, and each joined the first Union of states between 1777 and 1781, upon ratifying the Articles of Confederation, its first constitution. (A separate table is included below showing AoC ratification dates.) These states are presented in the order in which each ratified the 1787 Constitution, thus joining the present federal Union of states. The date of admission listed for each subsequent state is the official date set by Act of Congress.[a]
Enabling Act of 1889, authorizing residents of Dakota, Montana, and Washington territories to form state governments (Dakota to be divided into two states) and to gain admission to the Union
Enabling Act of 1906 authorizing residents of Oklahoma, Indian, New Mexico, and Arizona territories to form state governments (Indian and Oklahoma territories to be combined into one state) and to gain admission to the Union
^This list does not account for the secession of 11 states (Virginia, North Carolina, South Carolina, Georgia, Florida, Alabama, Mississippi, Tennessee, Arkansas, Louisiana, and Texas) during the Civil War to form the Confederate States of America, nor for the subsequent restoration of those states to the Union, or each state's "readmission to representation in Congress" after the war, as the federal government does not give legal recognition to their having left the Union. Also, the Constitution is silent on the question of whether states have the power to secede from the Union, but the Supreme Court held that a state cannot unilaterally do so in Texas v. White (1869).
^Also known as the "Three Lower Counties Upon Delaware." Delaware became a state on June 15, 1776, when the Delaware Assembly formally adopted a resolution declaring an end to Delaware's status as a colony of Great Britain and establishing the three counties as an independent state under the authority of "the Government of the Counties of New Castle, Kent and Sussex Upon Delaware."
^The Virginia General Assembly adopted legislation on December 18, 1789 separating its "District of Kentucky" from the rest of the State and approving its statehood.
^The exact date upon which Ohio became a state is unclear. On April 30, 1802 the 7th Congress had passed an act "authorizing the inhabitants of Ohio to form a Constitution and state government, and admission of Ohio into the Union." (Sess. 1, ch. 40, 2 Stat.173) On February 19, 1803 the same Congress passed an act "providing for the execution of the laws of the United States in the State of Ohio." (Sess. 2, ch. 7, 2 Stat.201) Neither act, however, set a formal date of statehood. An official statehood date for Ohio was not set until 1953, when the 83rd Congress passed a Joint resolution "for admitting the State of Ohio into the Union", (Pub.L. 83–204, 67 Stat.407, enacted August 7, 1953) which designated March 1, 1803, as that date.
^The Massachusetts General Court passed enabling legislation on June 19, 1819 separating the "District of Maine" from the rest of the State (an action approved by the voters in Maine on July 19, 1819 by 17,001 to 7,132); then, on February 25, 1820, passed a follow-up measure officially accepting the fact of Maine's imminent statehood.
^On May 13, 1862, the General Assembly of the Restored Government of Virginia passed an act granting permission for creation of West Virginia. Later, by its ruling in Virginia v. West Virginia (1871), the Supreme Court implicitly affirmed that the breakaway Virginia counties did have the proper consents necessary to become a separate state.
^When President Benjamin Harrison signed the statehood proclamations for North and South Dakota he shuffled the papers on his desk and covered up all but the signature line of the documents. No one knows which state he signed into existence first. North Dakota's proclamation was published first in the Statutes at Large, as it is first in alphabetical order.
^Brought into existence within moments of each other on the same day, North and South Dakota are the nation's only twin-born states.
^Jensen, Merrill (1959). The Articles of Confederation: An Interpretation of the Social-Constitutional History of the American Revolution, 1774–1781. University of Wisconsin Press. pp. xi, 184. ISBN978-0-299-00204-6.