The Mountain Standard Time Zone is a geographic region that keeps time by subtracting seven hours from Coordinated Universal Time (UTC). In the United States, the following states are part of the Mountain Standard Time Zone:
Additionally, the southwestern quadrant of North Dakota, the western half of South Dakota, the western third of Nebraska, the two most western 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, one county in Oregon is divided between the Mountain and Pacific Time Zones; most of the county in question (Malheur County) observes Mountain Time because of its economic ties to southwestern Idaho. Likewise, the town of West Wendover, Nevada observes Mountain Time because of its close economic ties with central Utah.
Arizona is part of the Mountain Standard Time Zone, but does not observe Daylight Savings Time, a period of time between April and October in which the Mountain Standard Time Zone keeps time by subtracting six hours from UTC. However, the Navajo Nation, the bulk of whose area is within Arizona, observes Daylight Savings Time throughout its territory.
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 MountainStandardTime Zone.
Four counties in Kansas are part of the MountainStandardTime Zone.
Arizona does not observe Daylight Saving Time, a period of time between April and October in which the rest of the MountainTime Zone keeps time by subtracting six hours from UTC (UTC-6.) However, the Navajo Nation, the bulk of whose area is within Arizona, observes Daylight Saving Time throughout its territory.