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The Mountain Time Zone is known simply as MT. Mountain Standard Time (MST) is used from November through to March in the US and Canada and is seven hours behind Coordinated Universal Time (UTC). Mountain Daylight Time (MDT), meanwhile, is used throughout the rest of the year during daylight savings periods and is six hours behind UTC. The state of Arizona, however, does not use MDT.
Colorado, Montana, New Mexico, Wyoming, and Utah are entirely contained within the Mountain Time Zone. Ten additional states (Arizona, Nevada, Texas, Kansas, Idaho, Oregon, Nebraska, Oklahoma, North Dakota, and South Dakota) are partially or majorly covered by the zone. In Mexico, five states and some islands are included in the Mountain Time Zone. Up in Canada, all of the Alberta province observes Mountain Time, and parts of British Columbia, Northwest Territories, Nunavut, and Saskatchewan also fit into this time zone.
Daylight Savings Time in the Mountain Time Zone
Daylight savings time was introduced in 1966 in time with the Uniform Time Act, designed to help save energy and allow people to enjoy more sunlight in summer evenings. The idea was first proposed by Benjamin Franklin in the 1700s and had been introduced in other countries before arriving in America. Originally, daylight savings applied from the first Sunday of April to the last Sunday in October.
Since then, the Energy Policy Act of 2005 has changed the rules for daylight savings time, extending the period of daylight savings from the second Sunday of March to the first Sunday of November. Almost all areas within the Mountain Time Zone switch to MDT during this period. The state of Arizona is one of the only US states to not use this system and neither does the state of Sonora in Mexico. These areas technically therefore observe MST all year long.