County Seat: Tucson
Founded: 1864
Area: 9,187 square miles
Population: 980,263 (2010)
Other Major Cities: Ajo, Green Valley, Marana, Oro Valley, Sahuarita
Geographic Highlights: Pima County’s Santa Catalina Mountains, topped by 9,130-foot Mount Lemmon, overlook Tucson, and the two sections of Saguaro National Park bracket the city on the east and west. There’s also the Tohono O’odham Nation, Buenos Aires National Wildlife Refuge and Organ Pipe Cactus National Monument.