Arizona Territory 1877. The capital was finally moved to Phoenix on February 4, 1889. The territory was admitted to the Union as the 48th state on February 14, 1912. Proclamation to the People of Arizona. Arizona Territory The Territory of Arizona (also known as Arizona Territory) was a territory of the United States that existed from February 24, 1863 until February 14, 1912, when the remaining extent of the territory was admitted to the Union as the state of Arizona. It was created from the western half of the New Mexico Territory during the American Civil War. Following the expansion of the
Admission to the Union of the established state as well as the Congress. It was anticipated that Kentucky (which was a part of Virginia), Franklin (which was a part of North Carolina, and later became part of the Southwest Territory), Vermont (to which New York asserted a disputed claim), and Maine (which was a part of Massachusetts), would become states. As a result of this compromise, new breakaway states are permitted to join the Union, but only with the proper consents. Shortly after the new Constitution went into effect Congress admitted Vermont and Kentucky on equal terms with the existing 13 states, and thereafter