The Mountain Time Zone of North America keeps time by subtracting seven hours from Coordinated Universal Time (UTC) when standard time (UTC−07:00) is in effect, and by subtracting six hours during daylight saving time (UTC−06:00).

In Canada, Mexico, and the United States, this time zone is generically called Mountain Time (MT). Specifically, it is Mountain Standard Time (MST) when observing standard time, and Mountain Daylight Time (MDT) when observing daylight saving time. The term refers to the Rocky Mountains.

Baja California Sur, Sinaloa, and Sonora in Mexico, and most of Arizona in the United States, do not observe daylight saving time (DST), and during the spring, summer, and autumn months they are on the same time as Pacific Daylight Time. The Canadian province of British Columbia and Yukon Territory observe permanent daylight saving time in the Pacific Time Zone, which is equivalent to year-round Mountain Standard Time.

The largest city in the Mountain Time Zone is Phoenix, Arizona; the Phoenix metropolitan area is the largest metropolitan area in the zone. The largest city that observes daylight saving time is Juárez, Chihuahua, Mexico.

The clock time in this zone is based on the mean solar time at the 105th meridian west of the Greenwich Observatory. In the United States, the exact specification for the location of time zones and the dividing lines between zones is set forth in the Code of Federal Regulations at 49 CFR 71.

Canada

One province and two territories are fully contained in the Mountain Time Zone:

One territory is split between the Mountain Time Zone, the Central Time Zone, and the Eastern Time Zone:

On September 24, 2020, Yukon switched to the Mountain Standard Time year-round. Previously, the territory had used the Pacific Time Zone with daylight saving time: UTC−8 in winter and UTC−7 in summer.

On March 8, 2026, most of British Columbia in the Pacific Time Zone adopted UTC−7 year-round but continue to call their time zone "Pacific Time". Southeastern parts of the province (near the Alberta border) continue to observe daylight saving time: UTC−6 in the summer and UTC−7 in the winter.

Alberta observed Mountain Time with daylight savings until 2026, when it switched to Central Time year-round. The western half of Saskatchewan observed Mountain Time without daylight savings until 1972 when it joined the rest of the province in Central Time.

Mexico

As of October 30, 2022, Mexico abandoned daylight saving time, with certain exceptions. The following states have an offset equal to Mountain Standard Time, there called the Zona Pacifico (Pacific Zone):

The following states have an offset equal to Mountain Daylight Time or Central Standard Time, there called the Zona Centro (Central Zone):

United States

Six states are fully contained in the Mountain Time Zone:

Three states are split between the Mountain Time Zone and the Pacific Time Zone. The following locations observe Mountain Time:

Six states are split between the Mountain Time Zone and the Central Time Zone. The following locations observe Mountain Time:

Major metropolitan areas

Alphabetical list of major cities located within the Mountain Time Zone. Cities in bold do not observe daylight saving time:

See also

Notes

External links