Daylight saving time: VERIFY Fact Sheet

Daylight saving time ends on Sunday, Nov. 3, 2024, which means most Americans will gain an hour of sleep.

People who live in states that observe daylight saving time will see more daylight in the mornings and darker evenings as we “fall back.”

Many VERIFY readers have sent us questions about daylight saving time, including if it will permanently end and whether it is observed in all 50 states. 

We’re answering five of the top questions about daylight saving time.

THE SOURCES

WHAT WE FOUND

THE ANSWER

There have been efforts to change the practice of switching the clocks, but none of them have been successful yet. 

The Sunshine Protection Act, a federal bill that would have made daylight saving time the “new, permanent standard time” for all states, has been introduced into Congress multiple times. But the legislation has never passed and become law. 

The bill gained some momentum when the Senate unanimously approved it in March 2022, but the House of Representatives didn’t pass it. 

Sen. Marco Rubio (R-Fla.) and Rep. Vern Buchanan (R-Fla.) frequently reintroduce the bill in their respective chambers, but the bill usually dies before it ever comes close to becoming law. 

There’s been little to no progress made on the most recent Senate and House versions of the Sunshine Protection Act that were introduced in March 2023. 

For now, millions of Americans will still change their clocks again to “fall back” to standard time on Sunday, Nov. 3, 2024, and move the clocks forward one hour to mark the beginning of daylight saving time on March 9, 2025.

Daylight saving time is not observed in all 50 states. Two states, Arizona and Hawaii, follow standard time year-round. 

Five U.S. territories – American Samoa, Guam, the Northern Mariana Islands, Puerto Rico and the Virgin Islands – also observe permanent standard time.

During World War I, Congress passed the Standard Time Act of 1918. The act adopted standard time in the U.S., and it established five standard time zones that are still in use today: the Eastern, Central, Mountain, Pacific and Alaskan zones.

The act also set a summer daylight saving time to begin on the last Sunday of March and conclude on the last Sunday in October. After World War I, Congress abolished summer daylight saving time at the federal level, but it was allowed to continue on a state-by-state basis.

As a result, the different local times between states led to confusion nationwide. This caused Congress to reexamine “the entire field of standard time” in 1961 so that times would be coordinated at the federal and state level.

This reexamination resulted in the passage of the Uniform Time Act of 1966, which mandated standard time within the existing time zones and established a system of uniform daylight saving time nationwide. Under the law, states may choose to exempt themselves from observing daylight saving time, and remain on standard time year-round. But states do not have the authority to be on permanent daylight saving time.

The U.S. has tried year-round daylight saving twice before: Once from 1942 to 1945 in response to World War II, and again as a “trial” in 1974.

After federally mandated daylight saving time was repealed following World War I, everyone went back to standard time year-round. But, in February 1942, the federal government reimplemented daylight saving time for WWII — this time as a year-round measure until the war ended.

The reason the government gave for “war time” — its WWII name for daylight saving time — was to attempt to conserve fuel and “promote national security and defense.”

The entire U.S. remained in year-round daylight saving time until the war’s end in 1945, when it was once again repealed in its entirety. 

In the 1970s, the U.S. tried year-round daylight saving time again. Then-President Richard Nixon announced the U.S. would stay in daylight saving time year-round for two years beginning in January 1974. He claimed it would save barrels of oil during the winter months to combat an ongoing energy crisis.

Congress used the 1974 decision as a “trial period” for permanent daylight saving time and charged the U.S. Department of Transportation (DOT) with studying its impact. In June 1974, the DOT gave Congress an interim report that said it supported “proceeding with the second year of the experiment,” but that it believed Congress should amend it to include four months of standard time from October 1974 to February 1975 — citing public opinion as a major reason for the change. Congress granted the request, and daylight saving time lasted just eight months in 1975. 

Congress did not continue implementing a year-round daylight saving time when the trial came to an end in the fall of 1975. Standard time returned, and daylight saving time started at its usual date in April 1976.

THE ANSWER

The DOT was tasked with finding an answer to whether daylight saving time actually results in electricity savings. 

The department submitted a report in 1975 that was reviewed a year later by the federal government’s National Bureau of Standards (NBS). The NBS review said the Transportation Department found electricity savings of 1% per day during March and April. However, the NBS questioned the Transportation Department’s conclusion, saying when it followed the same research technique, it found “no conclusive evidence for decreased production of electrical energy during Daylight Saving Time.”

In 2005, Congress approved extending daylight saving time by four weeks, so that it begins on the second Sunday in March and concludes on the first Sunday of November. Again, the government sought evaluations on whether the extension of daylight saving time would result in a reduction of electricity use.

The researchers found it actually cost residents an additional $9 million a year in energy costs when the state started observing the time change in 2006. That was because while the use of lighting dropped, there was more demand for heating and cooling.

THE ANSWER

Many countries don’t observe daylight saving time. But for those that do, the timing of when to change the clocks varies. 

Baja California, much of Chihuahua, much of Tamaulipas and much of Nuevo León in Mexico still observe daylight saving time at the same time as the U.S., according to timeanddate.com.

Many nations outside of North America and Europe, including India and China, don’t observe daylight saving time at all.

The Associated Press contributed to this report.