What happens Sunday
Clocks across most of the country will move back an hour Sunday as daylight saving time ends, NBC News reported. The change takes effect at 2 a.m. Unlike the spring switch, when an hour disappears, the clocks will go from 1:59 a.m. back to 1 a.m., repeating that hour. Cellphones and many other devices adjust automatically.
Sunsets will arrive earlier across the country through late fall and winter. Standard time will stay in place until daylight saving time resumes on March 14. Next year, it is due to end on Nov. 7.
The extra hour does not necessarily mean a longer night out. NBC News noted that some places let bars base last call on the updated time, but California requires bars to stop serving alcohol two hours past midnight regardless of the repeated hour.
How the system came about
The Standard Time Act of 1918 established daylight saving time to stretch summer daylight by pushing sunset an hour later, according to the U.S. Naval Observatory's Astronomical Applications Department, which NBC News cited. The idea was contested, and it was repealed the following year, leaving the matter to local governments.
It returned during the early days of World War II and was observed from 1942 to 1945. After the war, practices varied by state until the Uniform Time Act of 1966 standardized the dates while letting states and localities opt out.
Since 2007, daylight saving time has begun on the second Sunday in March and ended on the first Sunday in November. In 1974, President Richard Nixon briefly put the country on daylight saving time all year. The very dark mornings drew heavy criticism and were linked to children being hit by vehicles on their way to school. Congress reversed the change after Nixon resigned later that year, NBC News reported.
Who doesn't change clocks
Hawaii and most of Arizona do not observe daylight saving time, so their residents do not reset clocks twice a year, according to the Astronomical Applications Department. The National Conference of State Legislatures says U.S. territories also stay on standard time all year.
Internationally, the Pew Research Center found that only about a third of countries observe daylight saving time. About half of all countries used it at some point but have dropped it. Most Northern Hemisphere countries that still use it are in Europe and North America. South of the equator, where the seasons are reversed, the start and end dates are flipped.
The push to end clock changes
Nearly every state has considered legislation on whether to stay on standard time or daylight saving time, according to the National Conference of State Legislatures. Over the past seven years, 19 states have passed bills or resolutions for year-round daylight saving time. Federal law does not permit that, so those states would need Congress to approve a change.
The Senate passed the Sunshine Protection Act in 2022, which would make daylight saving time permanent, but it did not advance in the House. A version introduced in the House in January 2025 stalled in the Senate this summer.
In early October, President Donald Trump urged Senate Republicans on Truth Social to "get moving" on the bill. He said changing the clocks "costs our Country a fortune, is bad for Crime, stress on people, Sports, and just about everything else you can imagine," according to NBC News.
Experts remain divided
Some studies suggest that year-round daylight saving time could reduce traffic accidents and crime, NBC News reported. Many health and sleep researchers nonetheless oppose making it permanent. Their main concern is dark mornings, which would put more children on the road or walking to school before sunrise.
Sleep experts generally prefer the current back-and-forth to permanent daylight saving time. They point to higher risks of health problems when clocks are out of step with the sun.
