Arizona Time (Phoenix)

Arizona Time uses Mountain Standard Time (MST) year-round without observing daylight saving time. This makes Arizona UTC-7 permanently, which aligns it with Pacific Daylight Time in summer and Mountain Standard Time in winter. The state opted out of the Uniform Time Act in 1968, primarily because adding an extra hour of daylight to already scorching summer evenings was seen as undesirable — temperatures in Phoenix regularly exceed 110°F (43°C) in July. However, the Navajo Nation within Arizona does observe DST, creating a complex patchwork: the Hopi Reservation (surrounded by the Navajo Nation) does not observe DST, while the Navajo land around it does. This creates the unusual situation of driving through three time changes within a few miles. Arizona's no-DST policy makes it straightforward for international scheduling since its offset never changes, but it can confuse domestic travelers and businesses. The state is the most populous jurisdiction in the US to forgo DST, with over 7 million residents.