Where Is Area Code 303?
Area code 303 is a geographic area code in Colorado’s Mountain West region. It serves the Denver metropolitan area and nearby Front Range communities, including Aurora and Denver.
The coverage includes portions of Adams, Arapahoe, Boulder, Broomfield, Denver, Douglas, Jefferson, and Weld counties. Major communities include Boulder, Lakewood, Arvada, Westminster, Thornton, Centennial, Englewood, Golden, Longmont, and Littleton.
The area lies along Colorado’s Front Range, east of the Rocky Mountains. Notable features and landmarks include the Flatirons near Boulder, Red Rocks Amphitheatre in Morrison, Denver International Airport, and the University of Colorado Boulder. Area codes 720 and 983 also serve the same general region.
Cities and Communities in the 303 Area Code
- Arvada: Adams and Jefferson counties
- Aurora: Adams, Arapahoe, and Douglas counties
- Boulder: Boulder County
- Brighton: Adams and Weld counties
- Broomfield: City and County of Broomfield
- Castle Pines: Douglas County
- Castle Rock: Douglas County
- Centennial: Arapahoe County
- Cherry Hills Village: Arapahoe County
- Commerce City: Adams County
- Denver: City and County of Denver
- Edgewater: Jefferson County
- Englewood: Arapahoe County
- Erie: Boulder and Weld counties
- Federal Heights: Adams County
- Glendale: Arapahoe County
- Golden: Jefferson County
- Greenwood Village: Arapahoe County
- Highlands Ranch: Douglas County
- Lafayette: Boulder County
- Lakewood: Jefferson County
- Littleton: Arapahoe, Douglas, and Jefferson counties
- Longmont: Boulder and Weld counties
- Lone Tree: Douglas County
- Louisville: Boulder County
- Morrison: Jefferson County
- Northglenn: Adams County
- Parker: Douglas County
- Sheridan: Arapahoe County
- Superior: Boulder County
- Thornton: Adams and Weld counties
- Westminster: Adams and Jefferson counties
- Wheat Ridge: Jefferson County
History of Area Code 303
Area code 303 was established in 1947 as one of the original North American Numbering Plan area codes. It initially covered the entire state of Colorado. Growth in Colorado’s population, businesses, and telephone exchanges led to later geographic splits.
Area code 719 split from 303 in 1988 for southern and southeastern Colorado. Area code 970 split from 303 in 1995 for northern and western Colorado. Area code 720 became an overlay for the 303 region in 1998, and area code 983 became another overlay in 2022.
Key Facts About Area Code 303
- State and region: Area code 303 is in Colorado, in the Mountain West region of the United States.
- Primary city: Aurora, Colorado, is the primary city associated with area code 303; Denver is another major city in the service area.
- Type: Area code 303 is a geographic area code and one of the original North American Numbering Plan codes established in 1947.
- Time zone: Area code 303 uses Mountain Time.
- Population: No single official Census population total exists for area code 303 because telephone boundaries do not match census boundaries and overlap with other area codes.
- Historical splits: Area code 719 split from 303 in 1988, and area code 970 split from 303 in 1995.
- Overlays: Area code 720 overlaid the 303 region in 1998, and area code 983 overlaid the same Denver-area region in 2022.
- Landmarks and institutions: The 303 geographic area includes the University of Colorado Boulder, the University of Denver, Red Rocks Amphitheatre, and Denver International Airport.
Frequently Asked Questions
What state is area code 303 in?
Area code 303 is in Colorado.
What major cities use area code 303?
Major cities associated with area code 303 include Aurora, Denver, Boulder, Lakewood, Arvada, Westminster, Thornton, Centennial, Englewood, Golden, Longmont, and Littleton.
What time zone is area code 303 in?
Area code 303 is in Mountain Time.
Is area code 303 a toll-free number?
No, 303 is a geographic area code for Colorado rather than a toll-free code.