The Arizona Territory was administered by the U.S. Congress area in the United States, which consisted of 24 February 1863. Under the name of Arizona then it occurred in the 48th state on February 14, 1912, the Union and expanded so as the last state, the heartland of the 48 territorial contiguous states of the Union ( so-called Lower 48 ).
After the Mexican-American War in 1848, the Treaty of Guadalupe Hidalgo an area around the present-day states of New Mexico and Arizona, to walk New Mexico Territory, ceded by Mexico to the United States.
Around 1860 there was the first concrete considerations to share the New Mexico Territory and cleave an Arizona Territory. However, these proposals were rather of a divided into a northern and a southern territory of, rather than into a western and an eastern half, as it corresponded to the later states. Shortly before the American Civil War in 1861, the area divided into a northern part, which belonged to the Northern States, and a southern part of the Confederate States of America joined.
1863 Abraham Lincoln declared this territory for themselves. As the capital of Prescott was chosen. After the end of the Civil War took place then the division into a western part (Arizona Territory) and an eastern ( New Mexico Territory ). The Arizona Territory now bordered on the east by New Mexico, on the north by Utah, to the south the Mexican state of Sonora and to the west by Nevada and California, from which it was separated by the lower course of the Colorado River.