Tucson ( /tuːsɒn/ too-son) is a city in and the county seat of Pima County, Arizona, United States. The city is located 118 miles (188 km) southeast of Phoenix and 60 miles (98 km) north of the U.S.-Mexico border. The 2010 United States Census puts the city's population at 520,116 with a metropolitan area population at 1,020,200. In 2009, Tucson ranked as the 32nd largest city and 52nd largest metropolitan area in the United States. A major city in the Arizona Sun Corridor, Tucson is the largest city in southern Arizona, the second largest in the state after Phoenix. It is also the largest city in the area of the Gadsden Purchase. Tucson is home to the University of Arizona. Roughly 150 Tucson companies are involved in the design and manufacture of optics and optoelectronics systems, earning Tucson the nickname Optics Valley.
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 (some within or overlapping the city limits) include Casas Adobes, Catalina Foothills, Flowing Wells, Tanque Verde, Tortilita, New Pascua, Sahuarita 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.
The Tucson skyline is dominated by mountains in every direction. Close in to the city are the Santa Catalina Mountains to the north, the Rincon Mountains to the east, and the Tucson Mountains, closest of all, on the west side. Farther from the city proper, but still commanding the southern sky are the Santa Rita Mountains. And farthest of all, generally not visible from most of the city, are the Tortolita Mountain Range to the northwest. The highest point in the area is Mount Wrightson found in the Santa Rita Mountains at 9,453 feet (2,881 m) above sea level. Mount Lemmon is popularly thought to be higher, looming much closer over the city, but misses Mt. Wrightson's peak by 297 feet (91 m).