Southern Arizona covers the northern part of the Sonoran Desert and the northwestern tip of the Chihuahuan Desert. This area extends from Picacho Peak, south to the Mexican border, west to Ajo, and east to the New Mexico state border. Interstates 10 and 19 both lead through this area and converge in Tucson - Arizona's second-largest metropolitan area. Click on the links to the left below to learn more about each county. 
