Spanish expeditions encountered the Hopi and Zuni, sandstone villages of centuries-old, cliff-dwelling civilizations, and the more recently arrived nomadic Apache and Navajo. Governor Diego Ortiz Parilla established a fort at Tubac in 1753, and Tucson was founded in 1775. Apaches later forced the Spanish out of the region, although Tucson remained under a Mexican flag until the 1840s. Garrisons occupied the presidios at Tucson, Tubac, and Santa Cruz beginning in 1826, with their surrounding settlements precarious because the Apache had not conceded the frontier to Mexico. Mexico's independence from Spain in 1821, and the Mexican War (1846-1848), provided the opportunity for the United States to acquire the region north of the Gila River. The Gadsden Purchase in 1853 added the area south of the river. Both were part of the New Mexico Territory until the Arizona Territory was separated from it in 1863. Treks to the west for California's gold, primarily along Cooke's Wagon Route in the south, brought some settlement to the territory, principally along the Gila and Santa Cruz rivers. Arizona became a state in 1912, after a long struggle for that status. The ethnic composition of its population reflects its history. Mexican and Native American (Navajo, Hopi, Havasupai, Yuma, Cocopah, Mohave, Apache, Pima, and Maricopa) among them.

This guide offers a selection of resources and strategies for Arizona local history and genealogy research. These include the print and digital collections of the Library of Congress, as well as external repositories and web sites key to finding forebears in the Grand Canyon State.