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MT · UTC−7 standard · UTC−6 daylight · 6 states fully, 8 partly · Arizona keeps standard time
Mountain Time Zone map
The Mountain Time Zone covers the Rocky Mountain states from Montana to New Mexico and Arizona. It is the least populous of the four contiguous zones and the only one where a whole state, Arizona, skips daylight saving time.
Offset and daylight saving
Mountain Standard Time (MST) is UTC−7. Mountain Daylight Time (MDT), UTC−6, runs from the second Sunday in March to the first Sunday in November everywhere in the zone except Arizona. Arizona has not observed daylight time since 1968, so in summer Phoenix matches Los Angeles (Pacific Daylight Time is also UTC−7) and in winter it matches Denver. The exception inside the exception is the Navajo Nation, which covers the north-east corner of Arizona and does observe daylight time, while the Hopi Reservation inside the Navajo Nation does not.
States fully in the Mountain zone
Six states lie entirely in the zone, with a combined 2020 population of 19,975,430. Arizona alone accounts for 7,151,502 of that; Wyoming, with 576,851, is the least populous state in the country.
| State | Code | Capital | Population (2020) |
|---|---|---|---|
| Arizona | AZ | Phoenix | 7,151,502 |
| Colorado | CO | Denver | 5,773,714 |
| Montana | MT | Helena | 1,084,225 |
| New Mexico | NM | Santa Fe | 2,117,522 |
| Utah | UT | Salt Lake City | 3,271,616 |
| Wyoming | WY | Cheyenne | 576,851 |
States partly in the Mountain zone
Eight states are split. Idaho is the largest case: the zone boundary follows the Salmon River, so the panhandle north of it keeps Pacific time with Spokane, Washington, while Boise and the Snake River plain are Mountain. On the east side, the boundary with Central cuts through the Dakotas, Nebraska, Kansas and Texas, generally leaving the sparsely populated western fringe of each on Mountain time.
| State | Part in this zone | Rest of the state |
|---|---|---|
| Idaho | Southern Idaho, including Boise, Idaho Falls and Pocatello | Northern panhandle north of the Salmon River (Coeur d'Alene, Moscow, Lewiston) is Pacific |
| Kansas | Four western counties: Sherman, Wallace, Greeley, Hamilton | Rest of the state is Central |
| Nebraska | Western Panhandle (Scottsbluff, Alliance) and several central counties | Eastern two-thirds, including Omaha and Lincoln, is Central |
| Nevada | West Wendover only | Rest of the state is Pacific |
| North Dakota | South-west corner: Dickinson, Bowman, Hettinger | Rest of the state, including Bismarck and Fargo, is Central |
| Oregon | Most of Malheur County (Ontario) | Rest of the state is Pacific |
| South Dakota | Western half: Rapid City, the Black Hills | Eastern half, including Sioux Falls and Pierre, is Central |
| Texas | El Paso and Hudspeth counties | Rest of the state is Central |
Major cities on Mountain time
| City | Population (2020) |
|---|---|
| Phoenix, AZ | 1,608,139 |
| Denver, CO | 715,522 |
| El Paso, TX | 678,815 |
| Albuquerque, NM | 564,559 |
| Tucson, AZ | 542,629 |
| Mesa, AZ | 504,258 |
| Colorado Springs, CO | 478,961 |
| Salt Lake City, UT | 199,723 |
| Boise, ID | 235,684 |
Cheyenne, Billings, Santa Fe, Helena and Rapid City are also on Mountain time. Phoenix is the fifth-largest US city and the largest that does not change its clocks.
Where the boundaries run
With Central (east): from the Canadian border the line runs south through western North Dakota, along the Missouri River through South Dakota, across the Nebraska Sandhills, around the four western counties of Kansas, then along the Colorado and New Mexico state lines to the Rio Grande at El Paso. With Pacific (west): the Montana–Idaho state line down the Continental Divide as far as the Salmon River, the Salmon River across Idaho, the Idaho–Oregon and Idaho–Nevada state lines (with the Ontario, Oregon and West Wendover, Nevada exceptions), and the Nevada–Arizona line along the Colorado River.
Converting from Mountain
- Noon Mountain is 2 pm Eastern, 1 pm Central, 11 am Pacific, 10 am Alaska, 9 am Hawaii (8 am during daylight time).
- Noon MST is 19:00 UTC; noon MDT is 18:00 UTC. Arizona is 19:00 UTC all year.
- Between March and November Phoenix and Los Angeles show the same time; between November and March Phoenix and Denver do.
Other zones
Eastern · Central · Pacific · Alaska · Hawaii-Aleutian · all zones
Region maps for the same area: Mountain division, Rocky Mountain states, Southwest. See also the Continental Divide, which the zone's western boundary follows through Montana.