Mission 2000: A searchable database of Spanish mission records of the Pimería Alta (southern Arizona and northern Sonora, Mexico) containing baptisms, marriages, and burials from the late seventeenth century to the mid-nineteenth century.
Tohono O'odham Nation: History and culture of the indigenous people of what is now Santa Cruz County, Arizona.
Web de Anza: Contains information and documents related to the 1775-76 over land expedition from Sonora, Mexico to San Diego, CA. Part of the trail was through Santa Cruz County, AZ.