It's almost time to spring forward again.
Residents of California – as well as most of the United States – will turn their clocks ahead one hour at 2 a.m. Sunday for the start of daylight saving time.
However, this year is different than most. That's because the annual changing of the clock in spring and fall celebrates its 100th anniversary in the U.S.
First put into effect in this country on March 19, 1918, during World War I, it was used in an effort to preserve coal. The time shift, which is regulated by the U.S. Department of Transportation, happens on the second Sunday in March and will end – or "fall back" as its commonly referred to – on the first Sunday in November. It's been in use since 1966 under the Uniform Time Act.