With the exception of the Navajo NationArizona does not set the clocks forward 1 hour in spring for DST with the rest of the United States.
DST in the USMountain Standard Time
Almost all of Arizona is on the same time zoneMountain Standard Time (MST)all year. The time zone has a UTC offset of minus 7 hours (UTC−7).
It is also known as Mountain Timebut that term refers both to standard time and the time zone which is elsewhere used during DST: Mountain Daylight Time (MDT).
Time in ArizonaNavajo Nation Uses DST
The Navajo Nationa semi-autonomous Native American territoryfollows the United States DST schedule. It lies in northeastern Arizonanorthwestern New Mexicoand southeastern Utah.
During DST the Navajo Nationwhich includes the towns of Tuba CityChinleand Window Rocksets the clocks forward 1 hour to Mountain Daylight Time (MDT)which is 6 hours behind UTC (UTC−6).
No DST in Hopi Nation
A part of the Hopi Nationwhich lies within the Navajo Nationfollows Arizona’s no-DST rule. To confuse matters morethere is also an even smaller Navajo Nation territory within the Hopi Nation within the Navajo Nation. In addition to thisthere is another Hopi area adjacent to the main Hopi Nation territory.
As a resultif driving the correct route from the Arizona state border through both Navajo and Hopi areas to the other side you can end up changing your clock 7 times! For example: Tuba City (Navajo) and Moenkopi (Hopi) are only a couple of miles apartbut they have a 1-hour time difference during the summer. Jeddito (Navajo)in the middle of Hopi Nation territoryis 1 hour ahead of the surrounding areas during summer.
Opted Out of DST
Arizona is exempt from DST according to the US Energy Policy Act of 2005. The Act gives every state or territory the right to decide if it wants to use DST. If DST is observedthe state has to schedule DST in sync with the rest of the US: From the second Sunday in March until the first Sunday in November.
Because of Arizona’s hot climateDST is largely considered unnecessary. The argument against extending the daylight hours into the evening is that people prefer to do their activities in the cooler evening temperatures.
War Time DST
Arizona used DSTalong with the rest of the USduring World War I in an effort to conserve fuel for the war. Also known as War TimeDST was used in Arizona from March 31 to October 271918.
At that timeArizona had 2 time zones. Communities in the far west of the statenear Californiaused Pacific Time while the rest of Arizona observed Mountain Time.
Added 1 Hour during World War I
The state capital Phoenix and most of Arizona added 1 hour to Mountain Standard Time (MST) to what today is known as Mountain Daylight Time (MDT). When the War Time period endedmost of Arizonaincluding Phoenixreturned to MST.
The communities along the state’s western border added 1 hour to Pacific Standard Time (PST) and used what is known today as Pacific Daylight Time (PDT). These locations returned to PST again.
The next yearArizona joined the rest of the country for War Time from March 30 to October 261919. Like the year beforemost of the state added 1 hour to MSTwith the western border locations adding 1 hour to PST. The Yuma County communities in Arizona observed PDT from March 61921 until October 301921.
World War II
In 1942during World War IIPresident Franklin Delano Roosevelt introduced another period of War Timeand on February 91942most of Arizona moved to Mountain War Timeagain with the few western border communities observing Pacific War Time.
Buton January 11944 when most of Arizona returned to MSTthe western border communities remained on Pacific War Timewhile railroadsairlinesbus linesmilitary personneland interstate commerce continued to use Mountain War Time in line with a federal law.
Emergency Law
On April 11944an emergency law was passed to establish Mountain Time and Pacific Time as the state’s time zones. The law stated that DST was to be used from April 1 to September 30. Federal offices and departments were exempt from the law. Since this law was an emergency measureit became effective as soon as it was signed.
There is some uncertainty as to what happened nextbut it seems that most of Arizona moved to Mountain War Time (equivalent to Mountain Daylight Time) on March 171944even though the law indicates that the state was to remain on Mountain Standard Time until April 11944before changing to Mountain War Time.
Return to Standard Time
On October 11944most of Arizona returned to Mountain Standard Time (MST)while most of the Mohave County region changed to Pacific Standard Time (PST). Most parts of the state remained on MST until the mid-1960s.
In 1966the US Congress passed the Uniform Time Actwhich set a schedule for DST. It was still up to local jurisdictions to decide if DST was to be used. In 1967Arizona observed DST from the last Sunday of April to the last Sunday of October. On October 29 that yearit followed the rest of the country in returning to standard time. From that point onwardsmost parts of the state remained on MST.
DST Unpopular in Arizona
The DST trial in 1967 provoked so many negative reactions that DST was never used again. People in Arizonaincluding many businessesfarming communitiesand parentspreferred to remain on Mountain Standard Time throughout the year claiming that DST produced no benefits for them.
Most people believed that DST was not necessary given Arizona’s hot climateand cooler evenings were a benefit.
Howeversome businesses operating interstate complained that they had to keep reminding other states that Arizona doesn’t have DST.
The DST debateArizona on MSTNot PDT
There is a common misconception that Arizona is on Pacific Daylight Time (PDT) during the summer and on Mountain Standard Time (MST) during the winter. Because MST and PDT have the same UTC offset of minus 7 hours (UTC−7)Arizona has the same local time as neighboring states California and Nevada during the summer season.
Although the time is the sameArizona uses standard time (MST) all year. “Daylight” time zonessuch as MDTare mostly used for areas that switch to DST every year.
DST in the US
Hawaii is the only US state that does not use DST at all.
None of the US dependencies observe DST. This includes American SamoaGuamPuerto RicoNorthern Mariana Islandsthe US Minor Outlying Islandsand the US Virgin Islands.
Clock changes in the US