Area Code: 303

303 Area Code belongs to the state of Colorado. The following cities fall under this area code: Arvada, Aurora, Boulder, Brighton, Broomfield, Castle Rock, Castlewood, Columbine, Commerce City, Denver, Englewood, Highlands Ranch, Ken Caryl, Lafayette, Lakewood, Littleton, Longmont, Loveland, Northglenn, Parker, Southglenn, Thornton, Westminster, Wheat Ridge. There have been a total of 26165 Numbers for this area code.