Tucson is a city in and the county seat of Pima County, Arizona, United States, and is home to the University of Arizona. It is the second largest city in Arizona, with a population of 542,629 in the 2020 United States Census, while the population of the entire Tucson metropolitan statistical area is 1,043,433. The Tucson MSA forms part of the larger Tucson-Nogales combined statistical area. Tucson is the second most-populated city in Arizona behind Phoenix, both of which anchor the Arizona Sun Corridor. The city is 108 miles southeast of Phoenix and 60 mi north of the U.S.–Mexico border. Tucson is the 33rd largest city and the 58th largest metropolitan area in the United States.
Major incorporated suburbs of Tucson include Oro Valley and Marana northwest of the city, Sahuarita south of the city, and South Tucson in an enclave south of downtown. Communities in the vicinity of Tucson include Casas Adobes, Catalina Foothills, Flowing Wells, Midvale Park, Tanque Verde, Tortolita, and Vail. Towns outside the Tucson metro area include Benson to the southeast, Catalina and Oracle to the north, and Green Valley to the south.