Area code 303 is located in central Colorado, covering Denver, Aurora, Lakewood, Thornton, Arvada, Westminster and Centennial. It was put into service on January 01, 1947. Area code 303 is the older Numbering Plan Area in overlay complex 303/720/983.

Colorado Counties within Area Code 303:

Denver, Arapahoe, Jefferson, Adams, Boulder, Douglas, Broomfield, Weld, Elbert, Clear Creek, Gilpin, Park.

Colorado Major Cities within Area Code 303:

Denver, Aurora, Thornton, Lakewood, Arvada, Westminster, Centennial, Boulder, Highlands Ranch, Longmont, Broomfield, Castle Rock, Commerce City, Parker, Littleton, Northglenn, Brighton, Ken Caryl, Dakota Ridge, Englewood, Wheat Ridge, Lafayette, Columbine, Louisville, Sherrelwood, Golden, Erie, Welby, Greenwood Village, Superior, Federal Heights, Berkley, Cherry Creek, The Pinery, Castle Pines North, Lone Tree, Firestone, Gunbarrel, Roxborough Park, Evergreen, Stonegate, Derby, Frederick, Fairmount, Fort Lupton, Applewood, Twin Lakes, Cherry Hills Village, Sheridan,Dove Valley.

Area Code 303 Time Zone?

Mountain time zone is also known as America/Denver.

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