Clocks will fall back one hour at 2 a.m. on Sunday, Nov. 1, so people should set their clocks back before going to bed Saturday night. Daylight saving time begins on the second Sunday of March and ends on the first Sunday in November, under the Energy Policy Act of 2005. The clocks will spring forward again on March 14, 2027.
The Winter Solstice, the day with the fewest hours of sunlight, falls on Dec. 21 this year. Daylight after that date gets longer, first by seconds each day and then by minutes by February and March.
Daylight saving time began in 1918 during World War I as a wartime measure to extend the workday. The 2005 law lets states choose whether to observe it. Arizona, Hawaii and several U.S. territories stay on standard time. Texas has signed and proposed a permanent daylight saving calendar, but it will not take effect until federal congressional approval.