Arizona achieved statehood on February 14, 1912. 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.
The first European contact by native peoples was with Marcos de Niza, a Spanish Franciscan, in 1539. The expedition of Spanish explorer Coronado entered the area in 1540–1542 during its search for Cíbola. Father Kino was the next European in the region. He led the development of a chain of missions in the region and converted many of the Indians to Christianity. Spain founded presidios (“fortified towns”) at Tubac in 1752 and Tucson in 1775.
Arizona was initially administered by the United States government as part of the Territory of New Mexico until the southern part of that region seceded from the Union to form the Territory of Arizona. President Jefferson Davis approved and signed An Act to Organize the Territory of Arizona. The Southern territory supplied the Confederate government with men, horses, and equipment. Arizona has the westernmost military engagement on record during the Civil War with the Battle of Picacho Pass.
Arizona became a U.S. state on February 14, 1912. Arizona was the 48th state admitted to the U.S. and the last of the contiguous states to be admitted.