Where Is Area Code 720?
Area code 720 serves Boulder, Denver, and nearby communities in north-central Colorado. The calling area follows the Front Range urban corridor and lies in the Mountain West region. Area code 720 is a geographic code, not a toll-free code.
The 720 overlay covers communities in Adams, Arapahoe, Boulder, Broomfield, Denver, Douglas, Jefferson, and parts of Weld counties. Major population centers include Aurora, Lakewood, Arvada, Westminster, Thornton, Centennial, Castle Rock, Boulder, and Denver.
Notable features in the area include Boulder’s Flatirons and the Rocky Mountain foothills. The region also includes the University of Colorado Boulder and Denver International Airport.
Cities and Communities in the 720 Area Code
- Boulder, Boulder County
- Arvada, Jefferson County
- Aurora, Adams, Arapahoe, and Douglas counties
- Brighton, Adams County
- Broomfield, Broomfield County
- Castle Rock, Douglas County
- Centennial, Arapahoe County
- Commerce City, Adams County
- Denver, City and County of Denver
- Englewood, Arapahoe County
- Erie, Boulder and Weld counties
- Federal Heights, Adams 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
- Louisville, Boulder 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 720
Area code 720 was established in 1998 as an overlay for area code 303. It entered service on June 1, 1998, and added telephone numbers to the same broad geographic region instead of creating a separate geographic split.
Colorado originally received area code 303 in 1947. The state added area code 719 in 1988 and area code 970 in 1995 through geographic splits. Area code 983 joined the 303 and 720 overlay region on June 17, 2022, as demand for telephone numbers continued to grow in the Denver metropolitan area.
Key Facts About Area Code 720
- Area code 720 is a geographic area code in Colorado.
- Boulder is the primary city associated with area code 720.
- Area code 720 serves the Denver metropolitan area and nearby Front Range communities.
- Area code 720 is located in the Mountain West region of the United States.
- Area code 720 was created as an overlay, not as an original area code or geographic split.
- The 720 calling area includes the University of Colorado Boulder and Boulder’s Flatirons.
- Area code 720 shares its broad geographic region with area codes 303 and 983.
- Area code 720 uses Mountain Time.
Frequently Asked Questions
What state is area code 720 in?
Area code 720 is in Colorado.
What major cities use area code 720?
Major cities using area code 720 include Boulder, Denver, Aurora, Lakewood, Arvada, Westminster, Thornton, Centennial, Broomfield, Longmont, and Castle Rock.
What time zone is area code 720 in?
Area code 720 uses Mountain Time.
Is area code 720 a toll-free number?
No. Area code 720 is a geographic area code, not a toll-free code.