City of Tucson and Pima County have/had a hierarchical relationship

County seat City of Tucson
Home Pima County
Notes Pima County /ˈpiːmə/ is a county in the south central region of the U.S. state of Arizona. As of the 2010 census, the population was 980,263,[1] making it Arizona's second-most populous county. The county seat is Tucson,[2] where nearly all of the population is centered. The county is named after the Pima Native Americans who are indigenous to this area. Pima County includes the Tucson, Arizona Metropolitan Statistical Area. Pima County contains parts of the Tohono O'odham Nation, as well as all of the San Xavier Indian Reservation, the Pascua Yaqui Indian Reservation, Organ Pipe Cactus National Monument, Ironwood Forest National Monument and Saguaro National Park. The vast majority of the county population lies in and around the city of Tucson (2017 city population: 535,677), filling much of the eastern part of the county with urban development. Tucson, Arizona's second largest city, is a major commercial and academic center. Other urban areas include the Tucson suburbs of Marana (population 44,792), Oro Valley (population 44,350), Sahuarita (population 29,318), and South Tucson (population 5,643), a large ring of unincorporated urban development, and the growing satellite town Green Valley. The rest of the county is sparsely populated; the largest towns are Sells, the capital of the Tohono O'odham Nation, and Ajo in the county's far western region.
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