The ritual of changing the clocks twice a year to get more daylight has been in place for more than 50 years. But debates in state legislatures and Congress show that there’s some interest in stopping the process.
At least 45 states have considered or passed legislation to shift to permanent daylight saving time or permanent standard time. The Sunshine Protection Act, which would move the US to permanent daylight saving time, has been introduced to Congress several times, beginning in 2018. It was introduced again in 2021 where it passed in the Senate but died in the House, and was introduced most recently in 2025.
When does daylight saving time start and end?
In 2025, daylight saving time starts on Sunday, March 9, and will end on Sunday, November 2. It will begin again on Sunday, March 8, 2026, and run through Sunday, November 1, 2026.
Why did daylight saving time begin in the US?
Daylight saving time was originally implemented over 100 years ago, in 1918 during World War I to help conserve fuel and power and extend the workday. Working during the sunlight hours meant burning less fuel, and the ability to work later into the day. The Standard Time Act of 1918, which established the time change, also established the nation’s official time zones.
Congress repealed daylight saving time after WWI ended. It was enacted again in 1942 during WWII and repealed in 1945.
The daylight saving procedures most people are familiar with came about in 1966 with the passage of the Uniform Time Act, which re-established the twice-yearly time change.
The most recent change to how Americans “save” daylight was 2005's Energy Policy Act. This act extended daylight saving a few weeks, beginning the second Sunday of March, and ending on the first Sunday in November.
Which states have daylight saving time?
As of 2025, 48 states and Washington, DC, participate in daylight saving time.
If states do not want to change their clocks twice yearly, they can opt to remain on standard time permanently, as Arizona and Hawaii have opted to do. States cannot, however, opt for daylight saving time indefinitely.
Twenty states have passed laws or resolutions to observe daylight saving time permanently, but these can only take effect if Congress were to change federal daylight saving time law.
In 2023, Ohio passed legislation supporting the Sunshine Uniformity Act, which advocates passage of the federal law to be on daylight saving time permanently but does not change existing state law. In 2024, Kentucky proposed legislation to adopt daylight saving time pending passage of the Sunshine Uniformity Act, but it did not pass.
Are there benefits to daylight saving time?
There have been several studies on how seasonal daylight saving time impacts people.
In 1974, a Transportation Department daylight saving time study found no conclusive difference in energy usage, crime, travel times, or trade during the time shift. A separate report on whether the practice led to more traffic fatalities with school children was inconclusive.
In 2008, an Energy Department study showed energy consumption dropped 0.02% due to daylight saving time. The study also showed no “measurable impact” on vehicle gas consumption.
A 2020 academic study cited in a Congressional Research Service report found evidence of some increase in heart attacks during transitions to or out of daylight saving time.
What parts of the US get the most daylight during working hours?
The amount of daylight an area gets differs based on its location. Northern cities tend to get more dark days, or days with less than 10 hours of daylight in a year.
A city’s location within a time zone matters, too. The further west a city is in a time zone, the later its sunrises and sunsets will be.
Learn more about energy in the US get the data directly in your inbox by signing up for our weekly newsletter.
Keep exploring
Page sources and methodology
All of the data on the page was sourced directly from government agencies. The analysis and final review was performed by USAFacts.