Arizona's Unique Status
Arizona is the only state in the contiguous United States that does not observe daylight saving time. (Hawaii also opts out, but is not contiguous.) Every spring and autumn, while the rest of the nation resets its clocks, Arizonans leave theirs unchanged. This makes Arizona one of the few places in the U.S. where the time difference to other regions actually changes twice a year — from Arizona's own perspective, it is the rest of the country that keeps changing.
The Climate Argument
The primary reason Arizona rejected DST is straightforward: the desert heat. Phoenix regularly experiences summer temperatures above 43°C (110°F). In this environment, extra evening daylight is not a blessing — it means people are still running their air conditioners at full power an hour later in the day, increasing electricity use rather than reducing it. The cool hours of early morning are precious; Arizonans have no desire to lose them by shifting the clock forward.
Historical Decision
Arizona first participated in DST after the 1966 Uniform Time Act. However, the state legislature quickly exercised its right to opt out, doing so for the first time in 1967. The decision was driven by the Republican-controlled legislature reflecting agricultural and rural interests, as well as the basic logic that Arizona's year-round sunny climate makes DST less beneficial than in northern states.
The Navajo Nation Exception
The situation is complicated by the Navajo Nation, a tribal nation whose territory spans parts of Arizona, Utah, and New Mexico. The Navajo Nation observes DST to maintain consistent time across its entire territory — including the portions in New Mexico and Utah, which do observe DST. Within the Navajo Nation in Arizona, clocks do change twice a year.
Further complicating things: the Hopi Nation's reservation is entirely within the Navajo Nation's Arizona territory. The Hopi tribe follows Arizona's standard time and does not observe DST. This creates a remarkable "time zone donut hole" — travelers crossing the Navajo Nation, then the Hopi Reservation, then back into the Navajo Nation may cross through three different time offsets in a short drive.
Practical Effects
Arizona being on Mountain Standard Time (UTC−7) year-round means:
- In winter, Arizona is aligned with Mountain Time (same as Denver, Colorado).
- In summer, Arizona is aligned with Pacific Daylight Time (same as Los Angeles, California during DST).
This creates changing relationships with neighboring states throughout the year, requiring Arizonans who commute to or work frequently with Nevada or California to adjust their expectations seasonally.