Explainer: What is US Daylight Saving Time and When Do Clocks Change? By Reuters

Daylight Saving Time: A Reassessment of Its Relevance

Daylight saving time, impacting nearly 400 million individuals across North America, is once again being scrutinized as discussions about its necessity unfold. This biannual ritual of shifting clocks forward in the spring and back in the autumn has been a part of life in the United States, Canada, and Cuba for over a century. Yet, with new legislative initiatives and changing public attitudes, many are reconsidering its importance in modern society.

When Does Daylight Saving Time End in 2024?

In the United States and several other nations, daylight saving time will conclude on November 3, 2024, at 2 a.m. local time, providing people an extra hour of rest. While mornings will become brighter, evenings will see an earlier onset of darkness. The mnemonic "spring forward, fall back" serves as a practical reminder for adjusting clocks.

In contrast, countries like the UK and others in Europe will end daylight saving time on October 27.

In the U.S., daylight saving time consistently begins on the second Sunday in March and ends on the first Sunday in November. This schedule differs from that in the UK and European Union, where summer time starts on the last Sunday in March and concludes on the last Sunday in October.

When is the Shortest Day of the Year in 2024?

The winter solstice and the shortest day of the year will occur on December 21, 2024. Daylight hours can vary greatly depending on geographic location within the Northern Hemisphere; regions near the North Pole may experience total darkness, while areas further south still enjoy over ten hours of sunlight.

When Do Clocks Change in 2025?

In 2025, daylight saving time will commence on March 9 and wrap up on November 2.

The Origins of Daylight Saving Time in the U.S.

The concept of adjusting clocks according to seasonal changes dates back to the late 19th century when New Zealand entomologist George Hudson proposed it to promote energy conservation and extend daylight hours during the summer, benefitting his insect-collecting hobby after work. It did not gain widespread acceptance until World War I, when European countries sought ways to conserve energy. Germany was the pioneer, adopting daylight saving time in 1916, followed by the United States in 1918.

The practice underwent various changes until the United States established standardized time through the Uniform Time Act of 1966, allowing states to opt out but preventing permanent observance of daylight saving time.

The Controversy Surrounding Daylight Saving Time

A common misconception is that daylight saving time was introduced to benefit farmers; however, many in the agricultural community find it disruptive. Additionally, the original rationale of fuel conservation is under scrutiny, as studies show minimal energy savings associated with the time change.

Critics point to research indicating negative health impacts linked to daylight saving time, including increases in fatal traffic accidents, heart issues, strokes, and sleep deprivation in the days following the clock adjustments. A poll conducted in March 2023 revealed that 62% of Americans favor ending the clock-changing practice, although only half prefer to have permanent daylight saving time.

Do All U.S. States Observe Daylight Saving Time?

Not all states participate in daylight saving time. Hawaii and most of Arizona, apart from the Navajo Nation, do not observe it. The U.S. territories, including American Samoa, Guam, the Northern Mariana Islands, Puerto Rico, and the U.S. Virgin Islands, maintain permanent standard time.

While daylight saving time is common in the U.S., 19 states have enacted laws to adopt permanent daylight saving time if permitted by Congress.

Will the U.S. End Daylight Saving Time?

Currently, there are no immediate plans to abolish daylight saving time in the United States. Nevertheless, a federal proposal known as the Sunshine Protection Act aims to establish permanent daylight saving time. This legislation, introduced by a bipartisan group of senators, passed the Senate in 2022 but has yet to gain traction in the House of Representatives due to disagreements over standard versus permanent daylight saving time.

Last year, the senators reintroduced the bill, which has been forwarded to the Committee on Commerce, Science, and Transportation for review. To become law, the bill must pass both the Senate and House before being signed by the President.