This is a list of U.S. states by date of statehood, that is, the date when each U.S. state joined the Union. Although the first 13 states can be considered to have been members of the United States from the date of the Declaration of Independence – July 4, 1776 – or from the date on which they ratified the Articles of Confederation, they are presented here as being "admitted," as was Vermont, on the date each ratified the present United States Constitution; most other such lists, including the 50 State Quarters program, do the same.
The admission dates for later states were set by either the act of admission or a later resolution issued under that act, except for Ohio, whose date of admission was determined by act of Congress in 1953 as March 1, 1803, when its legislature first met because of a clerical error of omission—the original act omitted setting a date that the act took effect.
This list does not account for the secession of 11 states during the American Civil War to form the Confederate States of America, the subsequent restoration of those states to representation in Congress (sometimes called "readmission") between 1866 and 1870, or the end of Reconstruction in those states; since their secession was declared illegal by the Supreme Court in Texas v. White, they never legally left the Union. It also does not account for secessionist governments formed in two other states, as their Unionist governments generally remained in control.