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Mountain Time Zone

Time zone of North America

Wikipedia contributorsAdapted for Fathomly · View authors
4 min read
Source updated September 9, 2026
Image credit is listed at the end of this article.

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 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.

01Canada

One territory is fully contained in the Mountain Time Zone:

One province is split between the Mountain Time Zone and the Central 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". The Town of Golden and Columbia-Shuswap Regional District, which were previously on Mountain Time with daylight saving time, adopted permanent standard time, syncing the localities with the rest of the province besides the Regional District of East Kootenay by moving an hour back on November 1, 2026.

Alberta observed Mountain Time with daylight saving until 2026, when it switched to Central Time year-round. The western half of Saskatchewan observed Mountain Time without daylight saving until 1972 when it joined the rest of the province in Central Time. Following Alberta's switch to Central Time year-round, on August 14, 2026, the Regional District of East Kootenay in southeastern BC also switched to Central Time year-round from Mountain Time with daylight saving to maintain its alignment with Alberta.

Similarly, the Northwest Territories observed Mountain Time with daylight saving until 2026 before switching to Central Time year-round on August 21, 2026.

02Mexico

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 Pacífico (lit. 'Pacific Zone'):

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

03United 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:

04Major metropolitan areas

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

Watch videos about Mountain Time ZoneExplainers and documentaries on YouTube (opens in a new tab)

Sources and credits

This article is adapted from the Wikipedia article “Mountain Time Zone”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.

Images, from Wikimedia Commons:

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Related topics

Effects of time zones on North American broadcasting

The scheduling of television programming in North America must cope with different time zones. The United States (excluding territories) has six time zones (Hawaii-Aleutian, Alaska, Pacific, Mountain (including MST), Central and Eastern).