Tucson is a city in and the county seat of Pima County, Arizona, United States, located 118 miles (188 km) southeast of Phoenix and 60 miles (98km) north of the U.S.-Mexico border It is the largest city in southern Arizona and the second largest in the state after Phoenix. Tucson is home to the University of Arizona. The English name Tucson derives from the Spanish name of the city,meaning "(at the) base of the black [hill]", a reference to an adjacent volcanic mountain. Tucson is sometimes referred to as "The Old Pueblo". Much of Tucson's economic development has been centered on the development of the University of Arizona, which is currently the second largest employer in the city. Tourism is another major industry in Tucson, bringing in $2 billion-a-year and over 3.5 million visitors annually due to Tucson's numerous resorts, hotels, and attractions.