Santa Cruz is a county in southern Arizona. As of the 2010 census, its population was 47,420. The county seat is Nogales. The county was established in 1899. It borders between southern Arizona and northwestern Mexico's Sonora state.Santa Cruz County comprises the Nogales, AZ Micropolitan Statistical Area, which is also included in the Tucson-Nogales, AZ Combined Statistical Area.Santa Cruz County contains many vineyards.