In the United Stateswhile most states adjust their clocks twice a year to make better use of them daylightA select few have chosen not to engage in this practice.

Although Daylight Saving Time (DST) is widely used, some states and territories have chosen to maintain standard time year-round.

Which states don’t observe daylight saving time?

• Hawaii: This island nation, known for its tropical climate and geographical isolation, does not observe daylight saving time. Due to its proximity to the equator, fluctuations in daylight hours throughout the year are minimal, so changing the clocks is not necessary.
• Arizona (except Navajo Nation): Due to the extremely hot climate, Arizona has decided not to participate in Daylight Saving Time. By not moving the clocks forward or back, the state minimizes heat exposure during the hottest times of the day, resulting in less energy used for cooling. Notably, the Navajo Nation, which includes parts of Arizona, Utah and New Mexico, observes daylight saving time, unlike the rest of the state.

US territories that do not change their clocks

• Puerto Rico: As a Caribbean territory, Puerto Rico lies at a similar latitude to Hawaii, where variations in daylight duration are minimal throughout the year. Therefore, summer time is not taken into account.
• Guam: This US territory in the Pacific also observes standard time all year round. As in other island areas, the hours of the day do not vary enough to justify changing the clocks.
• American Samoa: Located in the South Pacific, this US territory follows a similar pattern to Guam and Puerto Rico and maintains standard time with no time adjustments.
• US Virgin Islands: Located in the Caribbean, these islands also avoid daylight saving time due to minimal variation in daylight hours.

Reasons for not introducing summer time

The states and territories that choose not to observe Summer time do this for practical and geographical reasons. In equatorial regions such as Hawaii, Puerto Rico and Guam, the variation in sunlight over the course of the year is so small that adjusting the clocks offers little benefit.

In the case of Arizona, the main reason is the climate. During the summer months, temperatures in the state can be extremely high. Maintaining standard time helps reduce heat stress and the need for air conditioning, which in turn reduces energy consumption.

The Navajo Nation: An Exception in Arizona

Interestingly, while Arizona as a whole does not observe daylight saving time, the Navajo Nation, which inhabits parts of Arizona, Utah and New Mexico, does. This exception exists because the Navajo Nation chose to use daylight saving time to maintain consistency with other areas of its territory outside of Arizona and to observe the time change.

Future prospects for summer time

While some states and territories have abandoned daylight saving time, the debate over its usefulness remains a topic of national debate. In recent years, there have been moves in several states to make daylight saving time permanent, although such changes require federal approval.

The diversity in the adoption of daylight saving time across the United States reflects the different needs and geographic conditions of states and territories. In the future, there may be further exceptions or even a national change in the way time is managed across the country.