The Mountain Time Zone of

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

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). The clock time in this zone is based on the

mean solar time Solar time is a calculation of the passage of time based on the position of the Sun in the sky. The fundamental unit of solar time is the day, based on the synodic rotation period. Traditionally, there are three types of time reckoning based ...

at the 105th meridian west of the Greenwich Observatory. In the United States, the exact specification for the location of

time zone A time zone is an area which observes a uniform standard time for legal, Commerce, commercial and social purposes. Time zones tend to follow the boundaries between Country, countries and their Administrative division, subdivisions instead of ...

s and the dividing lines between zones is set forth in the

Code of Federal Regulations In the law of the United States, the ''Code of Federal Regulations'' (''CFR'') is the codification of the general and permanent regulatory law, regulations promulgated by the executive departments and agencies of the federal government of the ...

at 49 CFR 71. In the United States, Canada, and Mexico, 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, which range from

British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...

to New Mexico. In Mexico, this time zone is known as the or ('Pacific Zone'). In the United States and Canada, the Mountain Time Zone is to the east of the

Pacific Time Zone The Pacific Time Zone (PT) is a time zone encompassing parts of western Canada, the western United States, and western Mexico. Places in this zone observe standard time by subtracting eight hours from Coordinated Universal Time ( UTC−08:00 ...

and to the west of the

Central Time Zone The North American Central Time Zone (CT) is a time zone in parts of Canada, the United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It ...

. In some areas, starting in 2007, the local time changes from MST to MDT at 2am MST to 3am MDT on the second Sunday in March and returns at 2am MDT to 1am MST on the first Sunday in November. Most of 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 Navajo Nation is the only part of Arizona that observes DST. Its territory lies mostly within Arizona but extends into

Utah Utah is a landlocked state in the Mountain states, Mountain West subregion of the Western United States. It is one of the Four Corners states, sharing a border with Arizona, Colorado, and New Mexico. It also borders Wyoming to the northea ...

and New Mexico (both observe DST statewide). Meanwhile, the Hopi Reservation, despite being completely surrounded by the Navajo Nation, does not observe DST, and neither do some Arizona state offices located within the Navajo Nation. The largest city in the Mountain Time Zone is

Phoenix, Arizona Phoenix ( ) is the List of capitals in the United States, capital and List of cities and towns in Arizona#List of cities and towns, most populous city of the U.S. state of Arizona. With over 1.6 million residents at the 2020 census, it is the ...

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

Canada

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

Alberta Alberta is a Provinces and territories of Canada, province in Canada. It is a part of Western Canada and is one of the three Canadian Prairies, prairie provinces. Alberta is bordered by British Columbia to its west, Saskatchewan to its east, t ...

Northwest Territories The Northwest Territories is a federal Provinces and territories of Canada, territory of Canada. At a land area of approximately and a 2021 census population of 41,070, it is the second-largest and the most populous of Provinces and territorie ...

* Yukon (no DST) On September 24, 2020, Yukon switched to the Mountain Standard Time year-round. Therefore, clocks in Yukon and Alberta are the same in the winter, and Alberta is one hour ahead in summer. Previously, the territory had used the Pacific Time Zone with daylight saving time: UTC−8 in winter and UTC−7 in summer. One province and one territory are split between the Mountain Time Zone and the

: *

– northeastern and southeastern regions *

– Tungsten One territory and one province are split between the Mountain Time Zone and the

: * Nunavut: Kitikmeot Region *

Saskatchewan Saskatchewan is a Provinces and territories of Canada, province in Western Canada. It is bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and to the south by the ...

: Lloydminster and vicinity

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: :* Baja California Sur :* Nayarit: except for the Bahía de Banderas municipality, which uses the Central Time Zone. :* Sonora :* Sinaloa :* Chihuahua: Observes Daylight Savings Time, only in northwestern border municipalities ( Janos, Ascensión, Juárez, Guadalupe, and Práxedis Gilberto Guerrero) :* Revillagigedo Islands ( Colima): three of the four islands have the same time as Mountain Time Zone: Socorro Island, San Benedicto Island and Roca Partida. The following states have an offset equal to Mountain Daylight Time:

United States

Six states are fully contained in the Mountain Time Zone: *

Colorado Colorado is a U.S. state, state in the Western United States. It is one of the Mountain states, sharing the Four Corners region with Arizona, New Mexico, and Utah. It is also bordered by Wyoming to the north, Nebraska to the northeast, Kansas ...

* Montana * New Mexico *

Wyoming Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho t ...

* Arizona (does not use daylight saving time except for Navajo Nation) Three states are split between the Mountain Time Zone and the

. The following locations observe Mountain Time: *

Idaho Idaho ( ) is a landlocked U.S. state, state in the Pacific Northwest and Mountain states, Mountain West subregions of the Western United States. It borders Montana and Wyoming to the east, Nevada and Utah to the south, and Washington (state), ...

: Southern Idaho and the portion of Idaho County south of the Salmon River *

Oregon Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...

: the majority of Malheur County * Nevada: West Wendover Five states are split between the Mountain Time Zone and the

. The following locations observe Mountain Time: * Kansas: Sherman, Wallace, Greeley and Hamilton counties *

Nebraska Nebraska ( ) is a landlocked U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Ka ...

: western one third * North Dakota: the southwest corner counties ( Adams, Billings, Bowman, Golden Valley, Grant, Hettinger, Slope, Stark) observe MST. The counties of McKenzie, Dunn, and Sioux are split. * South Dakota: western half * Texas: El Paso, Hudspeth, and northwestern Culberson counties

Major metropolitan areas

Alphabetical list of major cities located within the Mountain Time Zone. Cities in bold do not observe daylight saving time: * Albuquerque, New Mexico * Billings, Montana * Boise, Idaho * Boulder, Colorado * Calgary, Alberta * Cheyenne, Wyoming * Ciudad Juárez, Chihuahua * Ciudad Obregón, Sonora * Colorado Springs, Colorado * Culiacán, Sinaloa * Metropolitan Denver ** Arvada, Colorado ** Aurora, Colorado ** Centennial, Colorado ** Denver,

Lakewood, Colorado Lakewood is the List of municipalities in Colorado#Home rule municipality, home rule municipality that is the List of municipalities in Colorado, most populous municipality in Jefferson County, Colorado, United States. The city population was 15 ...

** Westminster, Colorado *

Edmonton Edmonton is the capital city of the Provinces and territories of Canada, Canadian province of Alberta. It is situated on the North Saskatchewan River and is the centre of the Edmonton Metropolitan Region, which is surrounded by Central Alberta ...

, Alberta * El Paso, Texas * Flagstaff, Arizona * Fort Collins, Colorado * Greeley, Colorado * Hermosillo, Sonora * La Paz, Baja California Sur * Lake Havasu City, Arizona * Las Cruces, New Mexico * Lethbridge, Alberta * Los Mochis, Sinaloa * Mazatlán, Sinaloa * Missoula, Montana * Nogales, Sonora * Metropolitan Phoenix ** Chandler, Arizona ** Gilbert, Arizona ** Glendale, Arizona ** Mesa, Arizona ** Peoria, Arizona **

** Surprise, Arizona ** Tempe, Arizona * Pueblo, Colorado * Rapid City, South Dakota * Red Deer, Alberta * San Luis Río Colorado, Sonora * Tepic, Nayarit * Tucson, Arizona * Wasatch Front ** Orem, Utah **

Provo, Utah Provo ( ) is a city in and the county seat of Utah County, Utah, United States. It is south of Salt Lake City along the Wasatch Front, and lies between the cities of Orem, Utah, Orem to the north and Springville, Utah, Springville to the south ...

** Salt Lake City, Utah ** West Jordan, Utah ** West Valley City, Utah * Yuma, Arizona

Notes

References

External links

World time zone map

History of U.S. time zones and UTC conversion

Official times across Mexico

U.S. time map
{{North American time zones Time zones Time in Canada Time in Mexico Time zones in the United States