Tucson is the county seat and most populous city in Pima County, Arizona, in the United States. With a population of 542,630 as of the 2020 census, it ranks as the second-most populous city in the state, following the capital city of Phoenix.
The Tucson metropolitan statistical area has an estimated 1.08 million residents and is ranked as the 52nd-largest metropolitan area in the United States. The city serves as one of the two anchors of the Arizona Sun Corridor alongside Phoenix. It is located approximately 108 miles southeast of Phoenix and 60 miles north of the United States–Mexico border. Tucson is also home to the University of Arizona.