Cities in area code 720

12 localities · NANPA data, current as of July 28, 2026.

Which places use area code 720? 12 rate centers in Colorado, the biggest being Denver, Longmont, Fort Lupton. Data below is NANPA's official prefix-to-rate-center mapping.

By numbering footprint the leading localities are Denver, Longmont, Fort Lupton, Georgetown, Allenspark-lyons, Deckers, Keenesburg and Hudson, and 3 smaller communities down to single-prefix localities. Prefix counts track lines in service, so the ranking is a reasonable proxy for where the code's subscribers actually are.

8 of the localities fall within FCC top-100 metropolitan statistical areas; the rest are smaller communities.

12 of these localities are also reachable through other area codes — overlay territory where the same place answers to several codes.

All of the code's territory keeps Mountain time.

Remember that people keep numbers when they relocate, so a 720 number is a where-it-was-issued fact, not a where-they-are fact.

FAQ

What is the biggest city in area code 720?

Denver holds the most active prefixes (678), making it the code's largest numbering locality.

How many places does 720 cover?

12 rate centers in Colorado hold active 720 prefixes, from Denver down to communities with a single prefix.

Does a 720 number guarantee the caller lives in one of these places?

No — the tables show where number blocks were issued. Porting and VoIP let people keep or acquire numbers anywhere.