Area Code 406
Montana
Area code 406 serves Montana, primarily Billings, in the Mountain Time (MT) time zone. It has served the region since 01-Jan-1947.
Published: Last reviewed: Verified against NANPA and FCC records
Demographics & Economics
- Total Population
- 1,616,483
- Population Density
- 4 people/sq mibelow U.S. average (U.S.: 95 people/sq mi)
- Median Household Income
- $71,283below U.S. median (U.S.: $80,734)
- Poverty Rate
- 12.0%near U.S. average (U.S.: 12.5%)
- Unemployment Rate
- 4.0%below U.S. average (U.S.: 5.2%)
- Education Attainment
- Bachelor's Degree+32.8%near U.S. average (U.S.: 35.7%)High School or Lower30.6%
Statistics are population-weighted aggregations from Census ACS 5-year estimates. Population figures are approximate — see Sources & Methodology for details on how area code populations are derived.
See how this area code compares to all US area codes in the income ranking and density ranking.
Time Zone
- Mountain Time (MT)
NANPA Relief Status
According to the latest NANPA analysis (July 2026), this area code is not currently listed as exhausting within the next 36 months. No relief planning is in progress for this NPA.
Source: NANPA NPA Relief Planning Reports · See all relief planning statuses
Current Time
Prefix Utilization
Geographic Coverage
State
MT
Major Cities
- Billings
- Missoula
- Great Falls
- Bozeman
- Helena
- Kalispell
- Belgrade
- Helena Valley Southeast
- Anaconda-Deer Lodge County
- Havre
- Evergreen
- Livingston
- Whitefish
- Helena Valley West Central
- Lockwood
- Laurel
- Sidney
- Lewistown
- Four Corners
- Columbia Falls
- Polson
- Orchard Homes
- Bigfork
- Helena Valley Northwest
and 473 more cities
Historical Timeline of Area Code 406
Area code 406 was created on January 1, 1947 as one of the original 77 US area codes in the North American Numbering Plan. Assigned the N0X format (middle digit 0) indicating a statewide code, 406 has covered the entire state of Montana for nearly eight decades without a single split or overlay. At 147,040 square miles, it is the largest geographic area code in the United States by land area. Source: NANPA.
Key milestones:
- 1947: Created as one of the original 77 US area codes in the North American Numbering Plan. Assigned the N0X format (middle digit 0), indicating a single-area-code state. Serves all of Montana. Source: NANPA
- 2011: Montana PSC filed petition with the FCC for delegated authority to implement number conservation measures (DA-11-2045, Docket 99-200/96-98). Source: FCC
- 2013: FCC granted Montana PSC authority to implement mandatory thousands-block number pooling (DA-13-1209). Carriers required to return unused 1,000-number blocks if using 10% or less. Extended projected exhaustion from 2019 into the 2030s. Source: FCC
- 2021: Montana transitioned to ten-digit dialing by October 24, 2021. The 988 central office code in the 406 area conflicted with the newly designated National Suicide Prevention Lifeline 3-digit access code. Source: NANPA
- 2026: PSC voted unanimously to request rate center consolidation from Qwest Corporation. Exhaustion forecast pushed to early 2033. Only 33 of 786 NXX codes remain unused; less than 50% of total available numbers are actively in service. Source: Daily Montanan
Regulatory History
Area code 406 has undergone five significant regulatory events over 15 years, centered on number conservation and the goal of preserving Montana's single-area-code status. Source: FCC
| Year | Event | Docket | Regulatory Action & Impact |
|---|---|---|---|
| 1947 | NANP Inception | AT&T / Bell System | Area code 406 established as one of the original 77 US NANP area codes, assigned to MT. |
| 2011 | PSC petition filed | DA-11-2045 | Montana PSC filed petition with FCC WCB seeking delegated authority to implement number conservation measures. This procedural step initiated the review process that would lead to mandatory pooling. Source: FCC |
| 2013 | Mandatory number pooling | DA-13-1209 | FCC granted Montana PSC authority to implement mandatory thousands-block number pooling. Carriers required to return unused 1,000-number blocks if using 10% or less. Extended projected exhaustion from 2019 into the 2030s. Source: FCC |
| 2017 | Exhaustion extended | N/A | FCC informed Montana PSC that mandatory pooling had extended 406's projected life into the 2030s, up from a previous exhaustion forecast of 2019. Montana confirmed as one of 12 remaining states with a single area code. Source: MT PSC |
| 2022 | PSC requests waiver | N/A | PSC submitted comments to FCC requesting waiver from three-year planning period rules and advocating for individual telephone number (ITN) pooling as an alternative to the 1000-number block system. Exhaustion then forecasted for late 2027. Source: MT PSC |
| 2026 | Rate center consolidation proposed | N/A | PSC voted unanimously to send letter to Qwest Corporation requesting analysis of rate center consolidation. Of 786 maximum NXX codes, 753 are assigned and only 33 remain unused. Less than 50% of total available numbers are actively in service. Exhaustion forecast pushed to early 2033. Source: Daily Montanan |
County Coverage
Population-weighted county share based on aggregated ZCTA population (100% = total mapped population for area code 406).
| County | Population | Share |
|---|---|---|
| Yellowstone, MT | 172,237 | 10.7% |
| Missoula, MT | 128,360 | 7.9% |
| Gallatin, MT | 124,953 | 7.7% |
| Flathead, MT | 112,723 | 7.0% |
| Cascade, MT | 87,821 | 5.4% |
| Lewis and Clark, MT | 75,278 | 4.7% |
| Chouteau, MT | 72,048 | 4.5% |
| Jefferson, MT | 60,446 | 3.7% |
| Big Horn, MT | 60,353 | 3.7% |
| Park, MT | 56,698 | 3.5% |
| Deer Lodge, MT | 49,907 | 3.1% |
| Silver Bow, MT | 48,629 | 3.0% |
| Ravalli, MT | 46,715 | 2.9% |
| Lake, MT | 42,684 | 2.6% |
| Carbon, MT | 28,692 | 1.8% |
| Madison, MT | 24,841 | 1.5% |
| Prairie, MT | 21,522 | 1.3% |
| Hill, MT | 21,143 | 1.3% |
| Blaine, MT | 21,040 | 1.3% |
| Rosebud, MT | 20,978 | 1.3% |
| Lincoln, MT | 20,656 | 1.3% |
| Broadwater, MT | 20,542 | 1.3% |
| Richland, MT | 17,011 | 1.1% |
| Sanders, MT | 16,833 | 1.0% |
| Granite, MT | 14,655 | 0.9% |
| Powder River, MT | 14,483 | 0.9% |
| Glacier, MT | 14,390 | 0.9% |
| Teton, MT | 13,459 | 0.8% |
| Custer, MT | 13,401 | 0.8% |
| Valley, MT | 13,357 | 0.8% |
| Roosevelt, MT | 12,993 | 0.8% |
| Garfield, MT | 12,595 | 0.8% |
| Fergus, MT | 12,007 | 0.7% |
| Dawson, MT | 11,993 | 0.7% |
| McKenzie, ND | 10,722 | 0.7% |
| Stillwater, MT | 10,644 | 0.7% |
| Toole, MT | 10,180 | 0.6% |
| Beaverhead, MT | 10,096 | 0.6% |
| McCone, MT | 9,739 | 0.6% |
| Powell, MT | 8,819 | 0.5% |
| Idaho, ID | 6,579 | 0.4% |
| Pondera, MT | 6,466 | 0.4% |
| Musselshell, MT | 5,903 | 0.4% |
| Mineral, MT | 5,795 | 0.4% |
| Phillips, MT | 5,433 | 0.3% |
| Petroleum, MT | 5,363 | 0.3% |
| Judith Basin, MT | 4,981 | 0.3% |
| Sheridan, MT | 4,382 | 0.3% |
| Fallon, MT | 4,248 | 0.3% |
| Sweet Grass, MT | 4,195 | 0.3% |
| Carter, MT | 3,917 | 0.2% |
| Meagher, MT | 2,883 | 0.2% |
| Wheatland, MT | 2,748 | 0.2% |
| Liberty, MT | 2,674 | 0.2% |
| Daniels, MT | 1,613 | 0.1% |
| Wibaux, MT | 1,164 | 0.1% |
| Golden Valley, MT | 1,031 | 0.1% |
| Treasure, MT | 898 | 0.1% |
| Divide, ND | 567 | 0.0% |
Area Code 406 Family Tree
Area code 406 is an original area code with no splits or overlays. It has been in service since 01-Jan-1947.
Call Context
This area code covers a primarily rural region in MT with low population density. The largest community is Billings.
Nearby Area Codes
Area codes geographically closest to 406.
