Across the United States, most states observe daylight saving time (DST), adjusting clocks forward in spring and back in fall. A small group of states and several territories keep a single time year-round, avoiding the biannual clock changes. This article details which states and territories do not observe DST, why the differences exist, and how it affects daily life, travel, and business.
Overview Of Year-Round Time Observance
Daylight saving time aims to extend evening daylight during warmer months, typically advancing clocks one hour in spring and reversing it in autumn. In the United States, federal guidance allows states to opt out of DST, but the vast majority participate. The choice to stay on standard time year-round is influenced by geography, energy use, public safety, and historical legislation.
States That Do Not Observe Daylight Saving Time
Two states currently do not observe DST year-round, remaining on standard time throughout the year. Arizona follows standard time annually, with an exception for the Navajo Nation, which observes DST. Hawaii remains on Hawaii-Aleutian Standard Time all year, never advancing clocks.
U.S. Territories With No Daylight Saving Time
Several U.S. territories do not observe DST, meaning their clocks stay the same year-round by law or practice. These territories include: Puerto Rico, U.S. Virgin Islands, Guam, American Samoa, and the Northern Mariana Islands. While not states, these regions share the practical effect of no clock changes and align most of the year with Eastern or other regional times depending on geographic position.
Impact Of Not Observing DST
- Travel and Scheduling: Flight times, conferences, and broadcast schedules may shift relative to states that observe DST, especially during spring and fall transitions.
- Business and Finance: Market hours and interstate commerce can require careful time-zone awareness to avoid miscommunication.
- Public Safety: Daylight availability affects road conditions and visibility, particularly after clocks change in neighboring regions.
- Public Health and Daily Life: Sleep patterns and circadian rhythms can be disrupted when nearby regions switch times.
Frequently Asked Questions
Does Arizona observe daylight saving time? Most of Arizona does not observe DST, staying on Mountain Standard Time year-round. The Navajo Nation, located in the state, does observe DST.
Is Hawaii on standard time year-round? Yes. Hawaii remains on Hawaii-Aleutian Standard Time throughout the year and does not participate in DST.
Do territories like Puerto Rico observe DST? No. Puerto Rico, along with several other territories, does not observe DST and maintains standard time year-round.