The U.S. currently has 13 statistical areas that have been delineated by the Office of Management and Budget (OMB). On July 21, 2023, the OMB delineated two combined statistical areas, seven metropolitan statistical areas, and four micropolitan statistical areas in Arizona. As of 2023, the most populous of these is the Phoenix-Mesa, AZ Combined Statistical Area, encompassing the area around Arizona's capital and largest city, Phoenix.