Tucson, often called "The Old Pueblo" and "Optics Valley," is a city in Pima County, Arizona, USA. It serves as the county seat and is the second-largest city in Arizona, with a population of approximately 540,000 in 2020. The Tucson metropolitan area has an estimated 1.08 million residents, making it the 52nd largest metropolitan area in the U.S. Tucson is known for its strong growth during the late 20th century and was the first American city to be designated a "City of Gastronomy" by UNESCO in 2015. Founded in 1775 as a Spanish military fort (Presidio San Agustín del Tucson), Tucson was originally named "Cuk Ṣon" by the local O'odham tribe, which means "the base [of the hill] is black" in reference to a basalt-covered hill called Sentinel Peak. Tucson served as the capital of the Arizona Territory from 1867 to 1877 and was the largest city in Arizona during the territorial period and early statehood. However, it was eventually surpassed in population by Phoenix by 1920. Tucson is a part of the Arizona Sun Corridor alongside Phoenix and is located about 108 miles southeast of Phoenix and 60 miles north of the U.S.-Mexico border. Major suburbs of Tucson include Oro Valley and Marana to the northwest, Sahuarita to the south, and South Tucson to the south of downtown. Nearby communities include Casas Adobes, Catalina Foothills, Flowing Wells, Midvale Park, Tanque Verde, Tortolita, and Vail, among others. Towns outside the Tucson metropolitan area include Three Points, Benson to the southeast, Catalina and Oracle to the north, and Green Valley to the south.