Covering an area of approximately 9,200 square miles, this is one of the oldest continuously inhabited areas of the United States. Native Americans have lived in this region from prehistoric times to the present, with the Tohono O’odham reservation the second largest in the nation. Created in 1864, Pima County included approximately all of southern Arizona acquired from Mexico by the Gadsden Purchase. In the middle of the 18th century, silver and gold discovered in the region drove development. And we’ve been growing ever since. Pima County is a county in the south central region of the U.S. state of Arizona. The population was 980,263 at the 2010 census. The county seat is Tucson, where nearly all of the population is centered. Other urban areas include Oro Valley, Marana, Sahuarita, Green Valley, Ajo, and South Tucson. DEPARTMENTS [Don't remove, needed for subpages] Pima County Administration Pima County Assessor Pima County Board Of Supervisors Pima County Communications Office Pima County Community Services, Employment & Training Pima County Constables Pima County Consumer Health & Food Safety Pima County Corrections Bureau Pima County Attorney Pima County Development Services Pima County District 1 Pima County District 2 Pima County District 3 Pima County District 4 Pima County District 5 Pima County Economic Development Pima County Elections Department Pima County Environmental Quality Department Pima County Facilities Management Pima County Finance Pima County Health Department Pima County Human Resources Pima County Information Technology Pima County Justice Courts Pima County One Stop Pima County Natural Resources, Parks and Recreation Pima County Public Library Pima County Recorder Pima County Sheriff's Department Pima County Transportation Pima County Treasurer Pima County Vital Records Pima Vocational High School Tucson Mountain Park