Tucson is the largest city in southern Arizona and the seat of Pima County. Its name is derived from the Tohono O'odham native Cuk Son, or "Black Foothills," a reference to the volcanic mountains that lie to the west. Tucson is a metropolis of glass and concrete set amidst a landscape of cactus forests, rolling hills, and craggy mountains.

In 1775, Lieutenant Colonel Hugo O'Conner of the Royal Spanish Army surveyed the area for the building of the Presidio of San Agustin del Tucson, which was completed in 1776. Things were tense at first between the Piman natives and the Spanish settlers, but they eventually developed a tenuous trust for one another as they worked together to cultivate the land and protect the settlements from Apache raids. In 1821, Mexico won its independence from Spain, and the Mexican flag was flown over the Presidio. Between the renewed Apache attacks and the lure of gold in California, the southern Arizona region was practically deserted. Tucson was the only populated settlement left in the area. With the Gadsden Purchase in 1853, southern Arizona (and Tucson) became a part of the United States.