303 area code is a telephone code used in Colorado. Together with 720 it covers Colorado central parts, Aurora, Boulder, Denver and Longmont. Area code 720 overlays the 303 – meaning that both of them serve the same area. 303 area code was created in 1947.
303 is “older” than 720. In the beginning, the entire Colorado area was using 303 area code. Then the population started to grow and it was necessary to split area codes. In the late eighties, 719 had to be split from 303, and by the middle of nineties, the same thing happened with 970, which was also split from 303 in 1995. 720 overlaid 303 in 1998.
303 and 720 are used in local calling area, meaning that the long distance calls cannot be made within this area. People who use these area codes have to dial 10 digits if they want to make a phone call, no matter how close the recipient is. 303 area code prevails and some users do not even write it in front of the phone number.
It is used in the following places: Bennett, Arvada, Black Hawk, Buffalo Creek, Cherry Hills,, Brighton, Bow Mar, Aurora, Denver, Boulder, Central City, Dupont, Evergreen, Keenesburg,Broomfield, Eastlake, Byers, Deckers, Wheat Ridge, Shawnee, Black Forest, Deer Trail, Edgewater, Conifer, Firestone, Dacono, Bailey, East Lake, Erie, Fort Logan, Elbert, Fort Lupton, Centennial, Adams City, Bond, Deckers, Fort Logan, Glendale, Grant, Henderson, Federal Heights, Allenspark, Commerce City, Dumont, Grants Ranch, Hudson, Empire, Foxton, Elizabeth, Castle Rock, Georgetown, Foxfield, Greenwood Village, Indian Hills, Henderson, Franktown, Kiowa, Eldorado Springs, Lakeside, Louisville, Frederick, Aspen Park, Englewood, Lafayette, Columbine Valley, Jamestown, Lakewood, Larkspur, Lone Tree, Lowry, Irondale, Littleton, North Glenn, Pine, Sedgwick, Niwot, Kittredge, Highlands Ranch, Nederland, Silver Plume, Montclair, Longmont, Parker, Sheridan, Strasburg, Rollinsville, Superior, Lyons, Golden, Watkins, Roggen, Westminster, Sedalia, Morrison, Idaho Springs, Ward, Welby, Thornton, Wattenburg.