Texas was annexed by the United States on December 29, 1845 , when Congress and President James K. Polk formally admitted Texas as the 28th state of the Union.

Quick Scoop: Texas Annexation

  • The key legal date for annexation is December 29, 1845 , when the U.S. accepted Texas as a state.
  • Texas then formally joined the Union with a transfer of authority on February 19, 1846 , often noted as the date it officially entered as a functioning U.S. state government.
  • A long political process led up to this, including:
    • U.S. joint resolution for annexation passed and signed on March 1, 1845.
* Texas convention and voters approving annexation in mid–1845 (July convention, October popular vote).

So if you’re answering “when was Texas annexed?” the historically standard answer is December 29, 1845 , with the note that formal transfer happened on February 19, 1846.

Information gathered from public forums or data available on the internet and portrayed here.