After the expansion of the New Mexico Territory in 1853 by the Gadsden Purchase, proposals for a division of the territory and the organization of a separate Territory of Arizona in the southern half of the territory were advanced as early as 1856.
Territorial secession conventions were called at Mesilla and Tucson in March 16, 1861 that adopted an Ordinance of Secession that declared itself independent of the United States and established the provisional Confederate Territory of Arizona with Owings as its governor, and petitioned the Confederate Congress for admission.
The territory of Arizona was admitted to the Union as the 48th state on February 14, 1912.