Mountain Time Zone

Mountain Time Zone
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). 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.
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, and Mountain Daylight Time (MDT) when observing daylight saving time. The term refers to the Rocky Mountains, which range from British Columbia 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 and to the west of the Central Time Zone.
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.
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 Navajo Nation, most of which lies within Arizona but extends into Utah and New Mexico (which do observe DST), does observe DST, although the Hopi Reservation, 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; the Phoenix metropolitan area is the largest metropolitan area in the zone.
Canada
One province and two territories are fully contained in the Mountain Time Zone:
Alberta
Northwest Territories
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 Pacific Time Zone:
British Columbia – northeastern and southeastern regions
Northwest Territories – Tungsten
One territory and one province are split between the Mountain Time Zone and the Central Time Zone:
Nunavut: Kitikmeot Region
Saskatchewan: Lloydminster and vicinity
Mexico
The following states have the same time as Mountain Time Zone:
Baja California Sur
Nayarit: except for the Bahía de Banderas municipality, which uses the Central Time Zone.
Sonora: no daylight saving time, always on MST.
Sinaloa
Revillagigedo Islands (Colima): three of the four islands have the same time as Mountain Time Zone: Socorro Island, San Benedicto Island and Roca Partida.
United States
Six states are fully contained in the Mountain Time Zone:
Colorado
Montana
New Mexico
Utah
Wyoming
Arizona (does not use daylight saving time except for Navajo Nation)
Three states are split between the Mountain Time Zone and the Pacific Time Zone. The following locations observe Mountain Time:
Idaho: Southern Idaho
Oregon: the majority of Malheur County
Nevada: West Wendover
Five states are split between the Mountain Time Zone and the Central Time Zone. The following locations observe Mountain Time:
Kansas: Sherman, Wallace, Greeley and Hamilton Counties
Nebraska: western one third
North Dakota: the SW 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:
Albuquerque, New Mexico
Boise, Idaho
Boulder, Colorado
Billings, Montana
Calgary, Alberta
Cheyenne, Wyoming
Chihuahua, Chihuahua
Ciudad Juárez, Chihuahua
Ciudad Obregón, Sonora
Colorado Springs, Colorado
Culiacán, Sinaloa
Metropolitan Denver
Arvada, Colorado
Aurora, Colorado
Centennial, Colorado
Denver, Colorado
Lakewood, Colorado
Westminster, Colorado
Edmonton, Alberta
El Paso, Texas
Flagstaff, Arizona
Fort Collins, Colorado
Greeley, Colorado
Hermosillo, Sonora
La Paz, Baja California Sur
Lake Havasu City, Arizona
Lethbridge, Alberta
Los Mochis, Sinaloa
Mazatlán, Sinaloa
Missoula, Montana
Nogales, Sonora
Metropolitan Phoenix
Chandler, Arizona
Gilbert, Arizona
Glendale, Arizona
Mesa, Arizona
Peoria, Arizona
Phoenix, Arizona
Surprise, Arizona
Tempe, Arizona
Provo, Utah
Pueblo, Colorado
Rapid City, South Dakota
Red Deer, Alberta
Salt Lake City, Utah
San Luis Río Colorado, Sonora
Tepic, Nayarit
Tucson, Arizona
West Jordan, Utah
West Valley City, Utah
Yuma, Arizona
See also
Effects of time zones on North American broadcasting
Notes
References
External links
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
Official times across Canada
Official times across Mexico
Canada time map
U.S. time map
Time zones
Time in Canada
Time in Mexico
Time zones in the United States