Wyoming has 1 active area code serving all cities and communities across the entire state in the Mountain Time Zone. Whether you need to identify an unknown caller, plan business communications, or schedule calls, this guide provides complete information about Wyoming’s area code 307.

Key Takeaways:

  • Wyoming uses only area code 307 for the entire state, one of 11 US states with a single area code
  • Area code 307 has served Wyoming since 1947 as one of the original 86 area codes
  • The state observes Mountain Time (MT) with Daylight Saving Time
  • Local calls require only 7 digits, no 10-digit dialing needed
  • With approximately 590,000 residents, one area code remains sufficient

Wyoming Area Code 307

Area CodePrimary Cities/RegionsTime ZoneTypeYear Introduced
307Entire state (Cheyenne, Casper, Laramie, Gillette, Rock Springs)Mountain Time (MT)Original1947

Area Code 307: Statewide Coverage

Area code 307 is Wyoming’s only telephone area code, covering all 23 counties and 99 incorporated municipalities across nearly 98,000 square miles.

Historical Background

Area code 307 was established January 1, 1947, as part of the original North American Numbering Plan. Wyoming received one of the original 86 area codes created during this initial rollout. The middle digit “0” indicated that the area code covered an entire state, a designation system used until 1953.

For over 78 years, Wyoming has maintained this single area code without requiring splits or overlays.

Geographic Coverage

Area code 307 serves all 23 Wyoming counties: Albany, Big Horn, Campbell, Carbon, Converse, Crook, Fremont, Goshen, Hot Springs, Johnson, Laramie, Lincoln, Natrona, Niobrara, Park, Platte, Sheridan, Sublette, Sweetwater, Teton, Uinta, Washakie, and Weston.

The code spans from Montana in the north to Colorado in the south, including Yellowstone National Park, Grand Teton National Park, and the Rocky Mountains.

Major Cities Served

Area code 307 serves Cheyenne (state capital, 65,800 residents), Casper (58,700), Gillette (33,900), Laramie (32,900), Rock Springs (23,000), Sheridan (18,700), and hundreds of smaller communities. It also covers tourist destinations like Jackson Hole and energy industry hubs in the Powder River Basin.

Why Wyoming Has One Area Code

Wyoming’s single area code reflects its status as the least populous state with approximately 590,000 residents. Each area code supports up to 7.9 million phone numbers. Wyoming’s population and business activity require far fewer numbers, keeping one area code sufficient.

Current Dialing Requirements

Wyoming allows 7-digit dialing for local calls. Because there’s no overlay area code, callers within Wyoming dial just the seven-digit local number without the area code prefix.

Calls from outside Wyoming require: 1-307-XXX-XXXX
International format: +1-307-XXX-XXXX

Future Projections

According to the Wyoming Public Service Commission, area code 307 should remain sufficient until approximately 2040. If a second area code becomes necessary, it would likely be an overlay requiring 10-digit dialing statewide.

Understanding Time Zones in Wyoming

Wyoming operates entirely within the Mountain Time Zone.

Time Zone Coverage

The entire state observes Mountain Time (MT) with no regional variations. Mountain Time is UTC-7 during standard time and UTC-6 during Daylight Saving Time.

Daylight Saving Time

Wyoming observes Daylight Saving Time. Clocks spring forward the second Sunday in March and fall back the first Sunday in November.

Time Differences from Other Zones:

  • 2 hours behind Eastern Time (New York, Atlanta)
  • 1 hour behind Central Time (Chicago, Dallas)
  • Same time as Colorado, Montana, New Mexico, Utah
  • 1 hour ahead of Pacific Time (Los Angeles, Seattle)

Wyoming Cities and Their Area Codes

  1. All Wyoming cities use area code 307:
  2. Cheyenne (307) – State capital, 65,800 residents, Laramie County
  3. Casper (307) – 58,700 residents, Natrona County, energy industry hub
  4. Gillette (307) – 33,900 residents, Campbell County, coal mining center
  5. Laramie (307) – 32,900 residents, Albany County, home to University of Wyoming
  6. Rock Springs (307) – 23,000 residents, Sweetwater County, historic mining town
  7. Sheridan (307) – 18,700 residents, Sheridan County, near Montana border
  8. Green River (307) – 11,800 residents, Sweetwater County
  9. Evanston (307) – 11,600 residents, Uinta County, near Utah border
  10. Riverton (307) – 11,100 residents, Fremont County
  11. Jackson (307) – 10,700 residents, Teton County, resort town
  12. Cody (307) – 10,000 residents, Park County, near Yellowstone
  13. Rawlins (307) – 8,600 residents, Carbon County
  14. Lander (307) – 7,600 residents, Fremont County
  15. Torrington (307) – 6,900 residents, Goshen County
  16. Powell (307) – 6,500 residents, Park County

How to Use Area Codes in Wyoming

Local Calling

Dial only the 7-digit phone number (XXX-XXXX) for calls within Wyoming. No area code or “1” prefix needed.

Long Distance from Other States

Dial 1-307-XXX-XXXX

International Calling

Dial +1-307-XXX-XXXX (or your country’s international access code + 1-307-XXX-XXXX)

Will Wyoming get a second area code?

Current projections suggest area code 307 remains sufficient until approximately 2040. If needed, a second area code would likely be an overlay, requiring 10-digit dialing for all calls statewide.

Are there toll-free numbers specific to Wyoming?

Toll-free numbers (800, 888, 877, 866, 855, 844, 833) are not geographically specific. Wyoming businesses may use toll-free numbers alongside their local 307 numbers, but these aren’t exclusive to the state.

Additional Resources

  • NANPA (North American Numbering Plan Administration): Official area code information
  • Wyoming Public Service Commission: State telecommunications regulatory authority
  • FCC (Federal Communications Commission): Federal telecommunications regulations