The Mountain Time Zone of North America keeps time by subtracting seven hours from Coordinated Universal Time (UTC-7) during the short days of autumn, winter and spring), and by subtracting six hours during the Daylight Saving days of spring, summer, and early autumn (UTC-6).

The time observed in this zone is called Mountain Standard Time (MST) when observing standard time; Mountain Daylight Time (MDT) when observing daylight savings.

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

Canada

---

In Canada, Mountain Time is observed in the province of Alberta, the Northwest Territories (except for Tungsten), the Kitikmeot Region of Nunavut and the part of Saskatchewan immediately surrounding the city of Lloydminster.

Mexico

---

In Mexico, Mountain Time covers the states of Baja California Sur, Chihuahua, Nayarit, Sinaloa, and Sonora. All these, with the exception of Sonora, observe DST from April to October.

United States

---

In the United States, the following states are part of the Mountain Time Zone:

• Arizona - always on MST - no daylight saving except in Navajo reservation

• New Mexico
• Wyoming
• Utah
• Colorado
• Montana
• Idaho (except northern panhandle)

Additionally, the southwestern quadrant of North Dakota, the western half of South Dakota, the western third of Nebraska, the two westernmost counties in Texas, and the bulk of Idaho are part of the Mountain Standard Time Zone. Four counties in Kansas are part of the Mountain Standard Time Zone. Also, the greater part of Malheur County, Oregon and the Nevada town of West Wendover is on Mountain Time. Jackpot, Nevada observes Mountain Time unofficially because of close economic ties with southern Idaho. Although officially on Mountain Time, Fort Pierre, South Dakota keeps Central Time because of its proximity to Pierre.

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.

Major metropolitan areas

---

• Albuquerque, New Mexico
• Billings, Montana
• Boise, Idaho
• Calgary, Alberta
• Chihuahua, Chihuahua
• Ciudad Juárez, Chihuahua
• Colorado Springs, Colorado
• Denver, Colorado
• Edmonton, Alberta
• El Paso, Texas
• La Paz, Baja California Sur
• Phoenix, Arizona (no DST)
• Salt Lake City, Utah
• Tucson, Arizona (no DST)

See also

---

• Time zone
• Hawaii-Aleutian Standard Time Zone
• Alaska Standard Time Zone
• Pacific Standard Time Zone
• Central Standard Time Zone
• Eastern Standard Time Zone
• Atlantic Standard Time Zone
• Newfoundland Standard Time Zone

Sources

---

• http://www.travel.com.hk/region/timezone.htm
• http://geography.about.com/library/misc/ntimezones.htm
• http://aa.usno.navy.mil/faq/docs/us_tzones.html
• http://www.worldtimezone.com/time-canada12.html

Time zones

山岳部標準時