Arizona states of Sonora and Baja California. Arizona is the 48th state and last of the contiguous states to be admitted to the Union, achieving statehood on February 14, 1912, coinciding with Valentine's Day. Historically part of the territory of "Alta California" in New Spain, it became part of independent Mexico in 1821. After being defeated in the Mexican–American War, Mexico ceded much of this territory to the United States in 1848. The southernmost portion of the state was acquired in 1853 through the Gadsden Purchase. Southern Arizona is known for its desert climate, with very hot summers and mild winters.
Admission to the Union phrase, "new States shall be admitted on the same terms with the original States", in the "new states" clause was defeated. That proposal would have taken the policy articulated in the Ordinance of 1784 and made it a constitutional imperative. Many delegates objected to including the phrase however, fearing that the political power of future new western states would ultimately overwhelm that of the established eastern states. Delegates, understanding that the number of states would inevitably increase, did agree to include wording into this clause to preclude formation of a new state out of an established one without the consent