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Most of Arizona Exempt from Daylight Saving Time

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Wednesday, July 23, 2014 at 8:04:34 PM MST

Arizona is one of the exceptions to the rule when it comes to observing daylight saving time in the United States. Most parts of the state, except the Navajo Nation community, observe Mountain Standard Time (MST) all year long. MST is also known as the Mountain Time Zone and is seven hours behind Coordinated Universal Time (UTC).

timeanddate.com explores the history of daylight saving time in Arizona, including why Arizona does not observe daylight saving and why the Navajo Nation land observes the schedule.

Illustration image

Most of Arizona observes Mountain Standard Time throughout the entire year.

©iStockphoto.com/Nitin Sanil

Background on Arizona Time

As a result of the Energy Policy Act of 2005, many parts of the United States observe daylight saving time on the second Sunday in March until the first Sunday in November. The Act does not alter the rights of the states and territories that choose not to observe daylight saving time. Arizona is one of the states in the United States that are exempt from daylight saving time.

According to the Arizona State Library, Archives and Public Records, daylight saving time in Arizona took place during World War I. On March 31, 1918, daylight saving time, which was also known as War Time, began in the United States to conserve fuel for the war effort during World War I. Arizona participated in this change but not in unison. Some communities in the far west, near California, were on Pacific Time while the rest of Arizona observed Mountain Time. The state’s capital city of Phoenix moved an hour ahead of MST and many communities along the state’s western border moved an hour ahead of Pacific Standard Time (PST). On October 27 that year, the United States returned to its standard time whilst Phoenix returned to MST and the communities on the western Arizona border returned to PST.

On March 30, 1919, Arizona joined the United States in returning to daylight saving time. However, not all of the state followed this change – Phoenix moved an hour ahead of MST but many western Arizona border communities moved an hour ahead of PST. Most of Arizona stopped observing daylight saving time on October 26, 1919, while the Yuma County communities observed Pacific Daylight Time (PDT) from March 6, 1921, until October 30, 1921.

On February 9, 1942, during World War II, most of Arizona moved to Mountain War Time but a few western Arizona border communities observed Pacific War Time. President Franklin Delano Roosevelt instituted War Time (daylight saving time) that year. On January 1, 1944, most of Arizona returned to MST . Some western Arizona border communities remained on Pacific War Time. Also, railroads, air lines, bus lines, military personnel and some engaged in interstate commerce continued to observe Mountain War Time in line with a federal law.

On April 1 that year, a law was passed to establish the state’s standard time. Parts of the state within the Mountain Time zone were to observe Mountain Time while areas of the state in the Pacific Time zone were to observe Pacific Time from October 1 to March 31. Then from April 1 to September 30 that year, the state's areas in the Mountain Time zone were to observe the equivalent of Mountain Daylight Saving Time while areas within the Pacific Time zone were to observe Pacific Daylight Saving Time. Common carriers engaged in interstate commerce and federal officers and departments were exempt from the law. Since this plan was an emergency measure, it became effective as soon as it was signed.

There is some uncertainty as to what happened next. Although it has been suggested that most of Arizona moved to Mountain War Time (or the equivalent of Mountain Daylight Saving Time) on March 17, 1944, the law indicates that the state was to remain on MST until April 1, 1944, and then to Mountain War Time.

On September 30, 1944, most of Arizona returned to MST and the Mohave County region changed to PST with some exceptions (“Clocks Turn Back Hour in State Tonight.” Arizona Republic, 30 Sep 1944, cited from the Arizona State library, Archives and Public Records). Most parts of the state remained on MST until the mid 1960s. Mohave Country joined the rest of the state in observing MST ("Standard Time Law Adopted." Arizona Republic, 8 Mar 1945, cited from the Arizona State library, Archives and Public Records).

In 1966 Congress passed the Uniform Time Act, establishing a beginning and end date for daylight saving time but it was up to local jurisdictions to decide if they wanted to use it. On April 30, 1967, Arizona observed daylight saving time from the last Sunday of April to the last Sunday of October. On October 29 that year, it followed the rest of the nation in returning to standard time (MST). From that point onwards, most parts of the state preferred to remain on MST.

Why was Daylight Saving Unpopular in Arizona?

Many people in Arizona including many businesses, farming communities and people with children, preferred to remain on MST throughout the year because daylight saving produced no personal benefits for them. They had tried it for one year in the 1960s but there was so much negative reaction that they never tried it again. Most people believed that a daylight saving schedule was not necessary for Arizona's hot climate. For many, it was easier to undertake personal activities, including sporting activities, when the temperature was cooler in the evening. Some also said that without daylight saving time, the state still managed to save heating and cooling energy in the summer (northern hemisphere) months.

However, some of the frustrations of observing MST throughout the year are that people in Arizona need to remind other states that it does not observe daylight saving time. This has, at times, been a small challenge for businesses that operate interstate.

Arizona On Mountain Standard Time, Not Pacific Daylight Time

There is a common misperception that Arizona is on Pacific Daylight Time (PDT) during the summer (in the northern hemisphere) and on Mountain Standard Time (MST) during the winter (in the northern hemisphere). Since MST’s time zone offset equals to that of PDT during the United States’ daylight saving period in the summer months, some may say that Arizona is on PDT because it shares the same time as two of its neighboring states, California and Nevada during this period.

However to be precise, Arizona is not on PDT because this term is a daylight saving time/summer time zone. It is generally only used during the daylight saving time for places that observe Pacific Standard Time (PST ) during the non-daylight saving period. As mentioned earlier, most parts of Arizona do not observe daylight saving time, so these parts remain on MST.

Why Arizona's Navajo Nation Observes Daylight Saving Time

The Navajo Nation lands, which extend to the states of Arizona, New Mexico and Utah, observe daylight saving time from April to October. It observes the daylight saving schedule because of its large size – it spans across three states.

During the daylight saving schedule, the Navajo Nation community moves the clock forward to six hours behind UTC, making it an hour ahead of the rest of Arizona. When it does not observe daylight saving time, it moves to clock backward to seven hours behind UTC, being in sync with the rest of Arizona, which observes MST. However, the Hopi Nation within the Navajo reservation follows the rest of the state by not observing daylight saving time.

Other States and Territories Without Daylight Saving

States and territories in the United States that do not observe daylight saving time, aside from most of Arizona, include: Hawaii, American Samoa, Guam, Puerto Rico, and the Virgin Islands. Some parts of Indiana did not observe daylight saving time in the past. However, the entire state is now united in observing daylight saving time since 2006 despite being split into different time zones.

Note: timeanddate.com wishes to thank the Arizona State Library, Archives and Public Records for providing permission to use its resources about Arizona’s time and daylight saving schedule. Also, all references to summer and winter in this article relate to the seasons in the northern hemisphere.

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