After the expansion of the New Mexico Territory in 1853, the fate of the nearby Arizona Territory was in question. In 1856, a petition was presented to the U.S. Congress requesting organization of the territory, but the proposal was defeated on the grounds that the population was too small, and because of the perception that the New Mexico Territory was populated with southern sympathizer who were interested in expanding slavery into the southwest.
The Confederacy regarded the territory as a valuable route for possible access to the Pacific Ocean, with the specific intention of capturing California. In July 1861, a small Confederate force of Texans under the command of Lieutenant Colonel John R. Baylor assaulted Fort Fillmore at Mesilla in the eastern part of the territory. After the fort was abandoned by the Union garrison, Baylor’s force cut off the fleeing Union troops and forced them to surrender. On August 1, 1861, Baylor issued a “Proclamation to the People of the Territory of Arizona”, taking possession of the territory for the Confederacy, with Mesilla as the capital and himself as the governor, establishing Confederate Arizona.
In March 1862, the U.S. House of Representatives, now devoid of the southern delegates and controlled by Republicans, passed a bill to create the United States Arizona Territory using the north–south border of the 109th meridian. The use of a north–south border rather than an east–west one denied a de facto ratification of the Confederate Arizona Territory. The house bill stipulated that Tucson was to be the capital. The final bill passed the Senate in February 1863 without the Tucson-as-capital stipulation and was signed into law by President Abraham Lincoln on February 24, the date of the official organization of the U.S. Arizona Territory.
The first capital was established in 1864 at Prescott, in the northern Union-controlled area. The capital was moved to Tucson in 1868, and back to Prescott in 1877. The capital was finally moved to Phoenix on February 4, 1889.
