Area Code 307

About Area Code 307

Area code 307 is a geographic telephone area code assigned to Cheyenne, Wyoming. It operates in the Mountain time zone and was first introduced in 1947. Original NANP code. State-wide Wyoming.

Within Wyoming, area code 307 is the only active area code, covering the entire state. The state's 584,057-person population (2023 Census Bureau estimate) is served by a combined 1 active code, with 307 primarily responsible for the Cheyenne region. Wyoming's state capital is Cheyenne, and its largest city is Cheyenne.

When you receive a call from a 307 number on your Caller ID, the call originated from a phone number assigned to the 307 area code — but be aware that Local Number Portability (in effect since 2003) means the caller could be physically located anywhere in the US or Canada. Area code 307 only confirms where the number was originally assigned.

Where is the 307 area code located?

Area code 307 is assigned to Cheyenne, Wyoming, in the Mountain time zone. The state of Wyoming uses 1 active area code, and 307 is the only one. Calls placed from the 307 area code originate from numbers assigned by NANPA — the North American Numbering Plan Administrator — and the 307 prefix appears on Caller ID for both landline and wireless calls placed from this region.

The Mountain time zone observes Daylight Saving Time, shifting from UTC-7 to UTC-6 in summer. The local time shown above is always current, so you can quickly check whether it's a reasonable hour to call back.

What cities and counties use the 307 area code?

The 307 area code serves 15 notable cities, listed below in order of population. The largest city in the 307 territory is Cheyenne (65,132 residents in Laramie County).

• Cheyenne, WY — 65,132 residents (20.7% of 307 numbers)
• Casper, WY — 58,763 residents (18.7% of 307 numbers)
• Laramie, WY — 32,381 residents (10.3% of 307 numbers)
• Gillette, WY — 33,403 residents (10.6% of 307 numbers)
• Rock Springs, WY — 23,085 residents (7.4% of 307 numbers)
• Sheridan, WY — 17,955 residents (5.7% of 307 numbers)
• Green River, WY — 11,236 residents (3.6% of 307 numbers)
• Evanston, WY — 11,538 residents (3.7% of 307 numbers)
• Riverton, WY — 10,794 residents (3.4% of 307 numbers)
• Jackson, WY — 10,560 residents (3.4% of 307 numbers)

Phone number format in area code 307

All phone numbers within area code 307 follow the standard North American 10-digit format:(307) NXX-XXXX. The NXX is the central office prefix (also called an "exchange") and XXXX is the subscriber line number. For long-distance calls within the NANP, dial 1 + 307 + NXX + XXXX. From outside North America, dial your country's international access code, then 1 (the NANP country code), then the 10-digit number.

If you need to verify whether a specific 307 number is wireless, landline, or VoIP, you can use our reverse phone lookup tool. Be aware that number portability means the area code no longer guarantees the caller's physical location — only where the number was first assigned.

History of area code 307

Original NANP code. State-wide Wyoming.

The original 86 area codes were assigned by AT&T and Bell Labs in 1947 as part of the North American Numbering Plan. At the time, rotary-dial phones meant codes with lower digits (like 212 for NYC, 213 for LA, 312 for Chicago) were given to the largest cities because they took less time to dial. Today's area code assignments still reflect those early choices, even though touch-tone and cell phones made the original reason obsolete.

Is the 307 area code safe to answer?

Area code 307 itself is a normal geographic code with no elevated spam risk. That said, scammers can spoof any area code — including 307 — so if you don't recognize the full number, let it go to voicemail and verify the caller's identity before calling back.