Tucson ( /ˈtuːsɒn/ TOO-son) is the county seat of Pima County, Arizona, United States, and is the home of the state's first university, The University of Arizona. The 2010 United States Census puts the city's population at 520,116, while the entire Tucson metropolitan area's population is 1,020,200. Tucson is the second-largest populated city in Arizona behind Phoenix, which both anchor the Arizona Sun Corridor. The city is located 118 miles (188 km) southeast of Phoenix and 60 miles (98 km) north of the U.S.-Mexico border. Tucson is the 32^nd largest city and 52^nd largest metropolitan area in the United States. Roughly 150 Tucson companies are involved in the design and manufacture of optics and optoelectronics systems, earning Tucson the nickname Optics Valley.