The 720 area code is a familiar sight to residents of the central United States, but it often raises questions due to its relationship with other local codes.
The 720 area code is a telephone area code for the state of Colorado, covering the core Denver Metropolitan Area, including the cities of Denver, Aurora, Boulder, Lakewood, and their surrounding suburbs. It is part of an overlay complex with the older 303 area code and the newer 983 area code, requiring mandatory 10-digit dialing for all local calls within this region.
This comprehensive guide details the location, major cities, time zone, and the essential dialing rules for the 720 area code.
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Location and Geographic Coverage of 720
The 720 area code covers the most densely populated and economically vital section of Colorado, often referred to as the Front Range Urban Corridor.
Primary Location and Time Zone
- State: Colorado (CO), United States.
- Time Zone: Mountain Time Zone (MT). This includes Mountain Standard Time (MST) and Mountain Daylight Time (MDT) during daylight saving periods. The time is typically two hours behind the East Coast (ET).
Major Cities in the 720 Area Code
The 720 area code does not cover the entire state (unlike the 970 and 719 area codes), but rather the major urban centers that constitute the Denver metro area:
- Denver: The state capital and largest city.
- Aurora: A large suburb east of Denver.
- Boulder: Home of the University of Colorado.
- Lakewood
- Littleton
- Westminster
- Arvada
- Centennial
- Longmont
The area code serves parts of Denver, Arapahoe, Jefferson, Adams, and Boulder counties.
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The Overlay Complex: 303, 720, and 983
The 720 area code was introduced to address the rapid depletion of phone numbers in the Denver area, which was originally served only by the 303 area code.
720 as an Overlay
- Origin: The 720 area code was established in 1998 as an overlay for the existing 303 area code.
- Function: An overlay means that both 303 and 720 numbers are assigned to the exact same geographic region.
The New 983 Overlay
Due to continued growth, the Denver metropolitan region reached number exhaustion again, leading to the approval and activation of a third overlay, the 983 area code, starting in 2022.
- The entire Denver metro area is now covered by a three-way overlay: 303 / 720 / 983.
Mandatory 10-Digit Dialing
Because of the overlay system, all phone users in the 720 area must adhere to mandatory 10-digit dialing for every local call.
- Rule: To complete any local call (even across the street), you must dial the full Area Code + 7-Digit Local Number.
- The system recognizes all three codes (303, 720, and 983) as local numbers when dialed with 10 digits.
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History, Culture, and Trust
The 720 area code, along with 303, has become synonymous with Colorado’s vibrant Front Range community, often referred to as the “Mile High City” culture.
- 303 Day: The original area code (303) is often celebrated by businesses and locals on March 3rd (3/03). While 720 is newer, it represents the modern, dynamic growth of the region.
- Trust: When conducting business or receiving calls in the Denver metro area, both 303 and 720 are recognized as local, legitimate area codes.
Frequently Asked Questions (FAQ)
What is the difference between area codes 303 and 720?
There is no geographical difference between the two. The 720 area code was established as an overlay to the 303 area code. Any new telephone line activated in the Denver metro region after 1998 may have received a 720 number, while older numbers kept their original 303 prefix.
Do I need to dial 1 before the 720 area code?
No, for local calls, you do not dial ‘1’. All local calls within the 303/720/983 region only require the 10-digit format: Area Code + 7-Digit Local Number. You only need to dial ‘1’ if the call is long-distance outside of the Denver metro area (e.g., calling 719 or 970).
Should I worry about calls from the 720 area code?
As a US metropolitan area code, 720 is frequently targeted by scammers using caller ID spoofing. If you receive an unsolicited call from a 720 number you don’t recognize, it is best to let it go to voicemail. Always avoid giving out personal or financial information to unknown callers.
