Arizona State Route 303 or Loop 303, also known as the Bob Stump Memorial Parkway, is a freeway that serves the west part of the Phoenix metropolitan area. The freeway, originally a two-lane rural highway, was maintained by Maricopa County until 2004 when the Arizona Department of Transportation again took control of upgrading the interim road to a freeway.

The Phoenix metropolitan area, also known as the Valley of the Sun, the Salt River Valley, metro Phoenix, or The Valley, is the largest metropolitan statistical area in the Southwestern United States, with its largest principal city being the city of Phoenix. It includes much of central Arizona. The United States Office of Management and Budget designates the area as the Phoenix–Mesa–Chandler Metropolitan Statistical Area (MSA), defining it as Maricopa and Pinal counties. It anchors the Arizona Sun Corridor megaregion along with the second-most populous metropolitan area in the state, the Tucson metropolitan area. The gross domestic product of the Phoenix metropolitan area was $255 billion in 2018, 16th highest amongst metro areas in the United States.