Nogales is a city in Santa Cruz County, Arizona. The population was 20,837 at the 2010 census and estimated 20,407 in 2014. Nogales forms part of the larger Tucson-Nogales combined statistical area, with a total population of 1,027,683 as of the 2010 Census. The city is the county seat of Santa Cruz County.Nogales, Arizona, borders the city of Nogales, Sonora, Mexico, and is Arizona's largest international border community. The southern terminus of Interstate 19 is located in Nogales at the U.S.-Mexico border; the highway continues south into Mexico as Mexico Federal Highway 15. The highways meeting in Nogales comprise a major road intersection in the CANAMEX Corridor, connecting Canada, the United States, and Mexico. Nogales also is the beginning of the Arizona Sun Corridor, an economically important trade region stretching from Nogales to Prescott, AZ, including the Tucson and Phoenix metropolitan areas.