Arizona highway sign with notice for travelers about local time standard.

Time in Arizona, as in all U.S. states, is regulated by the United States Department of Transportation[1] as well as by state and tribal law.

All of Arizona is in the Mountain Time Zone.[2] Since 1968, most of the state—except the Navajo Nation—does not observe daylight saving time and remains on Mountain Standard Time (MST) all year. This results in most of Arizona having the same time as neighboring California each year from March to November, when locations in the Pacific Time Zone observe daylight saving time.

Daylight saving time

Daylight saving time (DST) observance across Arizona. Green regions observe DST, grey do not.

Unlike most of the United States, Arizona does not observe daylight saving time (DST), with the exception of the Navajo Nation, which does observe DST. The Hopi Reservation, which is not part of the Navajo Nation but is geographically surrounded by it, also does not observe DST.[2] For this reason, driving the length of Arizona State Route 264 east from Tuba City while DST is in place involves six time zone changes in less than 100 miles (160 km).

Reasoning

Because of Arizona's hot climate, DST is largely considered counterproductive. The argument against extending the daylight hours into the evening is that people prefer to do their activities in the cooler morning temperatures. The Navajo Nation, a semi-autonomous Native American territory, follows the United States DST schedule. It lies in northeastern Arizona, northwestern New Mexico, and southeastern Utah and thus maintains the same time throughout tribal lands despite state borders.[3]

Legislative history

On March 21, 1968, the Arizona legislature passed the final version of SB 1, placing Arizona under standard time.[4]: 629 [5] The bill had been working its way through the legislature since January of that year, and was sponsored by state Senators Tenney, Goetze, Porter, Halacy, Garfield, Campbell, Lewis, Gregovich, Giss, Crowley, and Holsclaw. It passed the Senate 25–3–2, and afterwards the bill was passed by the House 49–1–10. It was approved by Governor Jack Williams the same day.[5]

tz database

The tz database version 2023d contains two entries for Arizona:

CC Coordinates TZ Comments UTC offset UTC offset DST Notes
US +332654−1120424 America/Phoenix MST - AZ (most areas), Creston BC −07:00 −07:00
US America/Shiprock −07:00 −06:00

Example

When daylight saving is not active, the time in Phoenix and Albuquerque, New Mexico, is the same (Mountain Standard Time), and both are one hour ahead of Los Angeles, California (Pacific Standard Time).

When daylight saving is active, the time in Phoenix (Mountain Standard Time) and Los Angeles (Pacific Daylight Time) is the same, and both are one hour behind Albuquerque (Mountain Daylight Time).

The time in Navajo Nation is always the same as in Albuquerque.

Example of times:
Time  California Arizona New Mexico Ref.
Los Angeles Phoenix Navajo Nation Albuquerque
Standard time (winter) 1 p.m. PST 2 p.m. MST 2 p.m. MST 2 p.m. MST [6]
Daylight time (summer) 2 p.m. PDT 2 p.m. MST 3 p.m. MDT 3 p.m. MDT [7]

References

  1. ^ "Uniform Time". US Department of Transportation. 13 February 2015. Archived from the original on 24 August 2018. Retrieved 24 August 2018. The U.S. Department of Transportation (DOT) oversees the Nation's time zones and the uniform observance of Daylight Saving Time. The oversight of time zones was assigned to DOT because time standards are important for many modes of transportation.
  2. ^ a b "Time Zones in Arizona, United States". timeanddate.com. Retrieved March 9, 2019.
  3. ^ "No DST in Most of Arizona".
  4. ^ "Session laws, State of Arizona, 1968, Twenty-Eighth Legislature, Second Regular Session, Second to Fourth Special Sessions". State of Arizona. Retrieved October 13, 2018.
  5. ^ a b "Journal of the Senate, State of Arizona, 1968, Twenty-Eighth Legislature, Second Regular Session, Fourth Special Session". Arizona Memory Project. 1968. p. 740.
  6. ^ "The World Clock Meeting Planner for March 1, 2019". timeanddate.com. Retrieved March 9, 2019.
  7. ^ "The World Clock Meeting Planner for April 1, 2019". timeanddate.com. Retrieved March 9, 2019.
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