Phoenix–Mesa Gateway Airport (IATA: AZA, ICAO: KIWA, FAA LID: IWA), formerly Williams Gateway Airport (1994–2008) and Williams Air Force Base (1941–1993), is in the southeastern area of Mesa, Arizona, and 20 miles (32 km) southeast of Phoenix, in Maricopa County, Arizona. The airport is owned and operated by the Phoenix–Mesa Gateway Airport Authority, and is a reliever airport for Phoenix Sky Harbor International Airport. It is a focus city for Allegiant Air.