Mountain Standard Time (MST) is UTC−7 (represented in the green area slightly left from center)

The Mountain Time Zone of North America keeps time by subtracting seven hours from Coordinated Universal Time, sometimes called Greenwich Mean Time (UTC−7) during the shortest days of autumn and winter, and by subtracting six hours during daylight saving time in the spring, summer, and early autumn (UTC−6). The clock time in this zone is based on the mean solar time of the 105th meridian west of the Greenwich Observatory.

In the United States and Canada, this time zone is generically called Mountain Time (MT). Specifically, it is Mountain Standard Time (MST) when observing standard time (Winter), and Mountain Daylight Time (MDT) when observing daylight saving time. In Mexico this time is known as the Pacific Zone. In the USA, the exact specification for the location of time zones and the dividing line between zones is set forth in the Code of Federal Regulations at 49 CFR 71.^[1]

The zone is one hour ahead of the Pacific Time Zone and one hour behind the Central Time Zone.

In some areas, starting in 2007, the local time changes from MST to MDT at 02:00 LST to 03:00 LDT on the second Sunday in March and returns at 02:00 LDT to 01:00 LST on the first Sunday in November.

Most of Arizona does not observe daylight saving time, and during summer months is on the same time as Pacific Daylight Time, though it is still called Mountain Standard Time in Arizona. The Navajo Nation, most of which lies within Arizona, does observe daylight saving time, although the Hopi Nation (as well as some Arizona state offices) lying within the Navajo Nation do not.

The largest city in the Mountain Time Zone is Phoenix, Arizona.

TV broadcasting in the Mountain Time Zone is typically tape-delayed one hour, so that shows match the broadcast times of the Central Time Zone (i.e. prime time begins at 7:00 p.m. MT following the same order of programming as the other two time zones).

[edit] Canada

The following provinces and areas are part of the Mountain Time Zone:

• Alberta
• the Northwest Territories (except for Tungsten)
• most of the Kitikmeot Region of Nunavut
• portions of southeastern and northeastern British Columbia
• the area of Saskatchewan immediately surrounding the city of Lloydminster

[edit] Mexico

The following states are part of the Mountain Time Zone:

• Baja California Sur
• Chihuahua
• Nayarit: Except from the Bahía de Banderas municipality which uses the Central time zone.
• Sinaloa
• Sonora: always on MST - no daylight saving time like Arizona.
• Revillagigedo Islands (Colima): 3 of the 4 islands uses the Mountain Time Zone, Isla Socorro, San Benedicto Island and Roca Partida.

[edit] United States

The following states or areas are part of the Mountain Time Zone:

• Arizona - no daylight saving time, always on MST, except in the Navajo Nation.
• Colorado
• Montana
• New Mexico
• Wyoming
• Utah
• Idaho - southern half, south of Salmon River
• Oregon - northern three quarters of Malheur County, on Idaho border
• North Dakota - southwestern quadrant, southwest of (Missouri River)
• South Dakota - western half
• Nebraska - western third
• Kansas - the seven counties along the Colorado border
• Oklahoma - Although the entire state is legally on Central Time, the unincorporated community of Kenton, near the extreme western end of the Panhandle, unofficially observes Mountain Time.
• Texas - the two westernmost counties (Hudspeth, El Paso) and a portion of Culberson County
• Nevada - the border towns of West Wendover (near Utah) and Jackpot (near Idaho)

Arizona does not observe daylight saving time. However, the Navajo Nation, the bulk of whose area is within Arizona, observes daylight saving time throughout its territory. The Hopi Reservation, an enclave inside the Navajo Nation, does not observe daylight saving time.

[edit] Zoneinfo

See also: List of zoneinfo time zones

 US 	+394421−1045903 America/Denver   ? US 	+433649−1161209 America/Boise    south Idaho & east Oregon US 	+364708−1084111 America/Shiprock Navajo US 	+332654−1120424 America/Phoenix  Arizona 

[edit] Major metropolitan areas

• Albuquerque, New Mexico
• Billings, Montana
• Boise, Idaho
• Calgary, Alberta
• Chihuahua, Mexico
• Ciudad Juárez, Mexico
• Cranbrook, British Columbia
• Edmonton, Alberta
• El Paso, Texas
• Fort McMurray, Alberta
• Fort St. John, British Columbia (no DST)
• Front Range, Colorado/Wyoming — north to south:
  • Cheyenne, Wyoming
  • Fort Collins, Colorado
  • Denver
  • Colorado Springs, Colorado
  • Pueblo, Colorado
• Hermosillo, Mexico (no DST)
• La Paz, Mexico
• Lethbridge, Alberta
• Phoenix, Arizona (no DST)*
• Rapid City, South Dakota
• Red Deer, Alberta
• Santa Fe, New Mexico
• Tucson, Arizona (no DST)
• Wasatch Front, Utah — north to south:
  • Ogden
  • Salt Lake City
  • Orem
  • Provo
• Yellowknife, Northwest Territories

*- Largest city in time zone

[edit] References

1. ^ The specification for the Mountain Time Zone in the United States is set forth at 49 CFR 71.8, and is listed in text and pdf formats.
   The boundary between Central and Mountain is set forth at 49 CFR 71.7, and is listed in text and pdf formats.
   The boundary between Mountain and Pacific is set forth at 49 CFR 71.9, and is listed in text and pdf formats.

[edit] Sources

• World time zone map
• U.S. time zone map
• History of U.S. time zones and UTC conversion
• Canada time zone map
• Time zones for major world cities
• The official U.S. time for the Mountain Time Zone (except Arizona)
• The official U.S. time for the Mountain Time Zone (Arizona)
• Official times across Canada