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Boulder, CO is currently using two area codes 303 and 720. Boulder, CO utilizes an area code overlay in which area codes
303 and 720 serve the same geographic area. Ten digit dialing (area code + seven digit number) is necessary in Boulder because two different homes in the same geographic area can have the same seven digit
phone number but each would have a different area code. The area code overlay which is in use in Boulder, CO today was established in 1998.
Area Code 303 which is still in use in Boulder, CO was one
of the original area codes established in 1947. At that time it covered the entire state of Colorado. The area code has been split numerous times. Today, in addition to Boulder, CO, area codes 303 and 720
serve the larger communities of Arvada, Aurora, 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. |
