Area Code 303

Area Code 303 History:

01/01/1947
Area code 303 was officially put into service. In 1988 Area code 303 was split to form area code 719. In 1995 area code 303 was split to form area code 970. In 1998 area code 303 was overlaid with area code 720.

06/17/2022
Area code 983 was put into service as an all services overlay of area codes 303 and 720. Ten digit dialing (area code + seven digit number) is necessary in the 303/720/983 overlay because different homes in the same geographic area can have the same seven digit phone number but each would have a different area code.

Counties in Colorado within area code 303 include:

Adams County, Arapahoe County, Boulder County, Broomfield County, Clear Creek County, Denver County, Douglas County, Eagle County, El Paso County, Elbert County, Gilpin County, Jefferson County, Park County, Sedgwick County, and Weld County.

Major cities or places in Colorado within area code 303 include:

Area codes 303 and 720 serve central Colorado including the larger cities and communities of 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 and Wheat Ridge in addition to many smaller communities.