303 Area Code

The 303 area code is found in the state of Colorado, and spans 17 different Counties. Listed below are the 17 Counties that reside inside of the 303 area code. Included under the Counties are the cities within the given County.
Adams County Colorado
Aurora, Bennett, Brighton, Commerce City, Denver, Dupont, Eastlake, Henderson, Strasburg, Thornton, Watkins, Westminster
Arapahoe County Colorado
Aurora, Byers, Deer Trail, Denver, Englewood, Littleton
Boulder County Colorado
Allenspark, Boulder, Eldorado Springs, Erie, Hygiene, Jamestown, Lafayette, Longmont, Louisville, Lyons, Nederland, Niwot, Pinecliffe, Ward
Broomfield County Colorado
Broomfield
Clear Creek County Colorado
Dumont, Empire, Georgetown, Idaho Springs, Silver Plume
Denver County Colorado
Denver
Douglas County Colorado
Castle Rock, Franktown, Larkspur, Littleton, Lone Tree, Louviers, Parker, Sedalia
Elbert County Colorado
Elizabeth, Kiowa
El Paso County Colorado
Elbert, Monument
Gilpin County Colorado
Black Hawk, Central City, Rollinsville
Jefferson County Colorado
Arvada, Broomfield, Buffalo Creek, Conifer, Denver, Evergreen, Golden, Idledale, Indian Hills, Kittredge, Littleton, Morrison, Pine, Wheat Ridge
Larimer County Colorado
Berthoud, Loveland
Morgan County Colorado
Fort Morgan
Park County Colorado
Bailey, Grant, Shawnee
Summit County Colorado
Breckenridge
Teller County Colorado
Woodland Park
Weld County Colorado
Brighton, Dacono, Firestone, Fort Lupton, Frederick, Greeley, Hudson, Keenesburg, Longmont, Platteville, Roggen