Santa Cruz County, Arizona: History
Santa Cruz County, formed on March 15, 1899, out of what was then Pima County, is named after the Santa Cruz River. The river originates in the Canelo Hills in the eastern portion of the county, crosses south into Mexico near the community of Santa Cruz, Sonora, and then bends northwards returning into the United States (and Santa Cruz County) east of Nogales.
Father Eusebio Kino, an Italian explorer and missionary in the service of the Spanish Empire, named the Santa Cruz River–"holy cross" in Spanish–in the 1690s. In addition, Kino founded several missions to evangelize the different O'odham peoples living along the banks of the Santa Cruz River, including Missions San Cayetano del Tumacácori (1691) and San Gabriel de Guevavi (1691), as well as Los Reyes de Sonoita (1692) near Sonoita Creek. Along the river, but outside the boundaries of Santa Cruz County, Kino also founded Mission San Xavier del Bac (1692) near Tucson, Arizona, and Mission Santa Maria del Pilar (1693) in what is now Santa Cruz, Mexico. Kino's San Cayetano and San Gabriel missions were destroyed in the O'odham peoples' 1751 Pima Revolt and rebuilt as Missions Los Santos Ángeles de Guevavi (1751), San José de Tumacácori (1753), and San Cayetano de Calabazas (1756). The ruins of all three of these later missions are now protected by Tumacácori National Historical Park. Disease, warfare, overwork, and changes in land ownership during Spanish colonization led to the demographic decline of the O'odham peoples of Santa Cruz County.