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 ColumbiatoNew Mexico. In Mexico, this time zone is known as the tiempo de la montañaorzona Pacífico ("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.[4] 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.
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.[5]
One province and one territory are split between the Mountain Time Zone and the Pacific Time Zone:
As of October 30, 2022, Mexico abandoned daylight savings time, with certain exceptions.
The following states have the same time as Mountain Time Zone:
^The specification for the Mountain Time Zone in the United States is set forth at 49 CFR 71.8.[1] The boundary between Central and Mountain time zones is set forth at 49 CFR 71.7,[2] and the boundary between Mountain and Pacific time zones is set forth at 49 CFR 71.9.[3]
