Prior to the adoption of its name for a U.S. state, Arizona was traditionally defined as the region south of the Gila River to the present-day Mexican border, and between the Colorado River and the Rio Grande. It encompasses present-day Southern Arizona and the New Mexico Bootheel plus adjacent parts of Southwestern New Mexico. This area was transferred from Mexico to the United States in the Gadsden Purchase of 1853. Mining and ranching were the primary occupations of traditional Arizona's inhabitants, though growing citrus fruits had long been occurring in Tucson. History Pre Civil War Socio-politically, some of the founders of Arizona were from areas which were once the Republic of Texas, though many were from the area's heartland around Tucson, Arizona, settlers who had flocked to the region during the California Gold Rush of the 1840s. They maintained their eastern links via Mesilla, on traditional Arizona's border with Texas, to San Antonio, Texas. Most others were from elsewhere in the United States, as opposed to the Mexican citizens from Sonora and settlers from other settlements of the Midwest. Texas was the lifeline for Arizona, but only until California was established as a U.S. state, meaning Arizona had access to two separate lines of communications and food for frontier settlements. The main line was the Butterfield Overland Mail company, which ran through southern Arizona. Traditional Arizona was never part of William Walker's Republic of Sonora, as it was created in January 1854, a year after the Gadsden Purchase which put traditional Arizona under United States control. Civil War The closure of the mail line was one of the main reasons Arizona would secede from the Union and petition to join the Confederate States, one other main concern for the creation of Arizona Territory was the problem of constant Apache attacks in Arizona's southern frontier. Arizonans were incensed by the fact that there were not sufficient U.S. soldiers in the region to protect them from attack. The aim of becoming a separate American territory was realized after the First Battle of Mesilla when future governor, John R. Baylor defeated the Union garrison of Fort Fillmore with help from Arizonan militia. Mesilla and Tucson would become important towns for the Confederate war effort in the region. Tucson was an old Spanish presidio, protected by high adobe walls and had already been the scene of several Apache battles in the past. Tucson was