The clocks change twice each year to accommodate Daylight Saving Time. In the U.S., this time period begins on the second Sunday in March and ends on the first Sunday in November.
Clocks move forward one hour in March and move backward one hour in November. Most people remember the changes with the catch phrase "spring forward, fall back," referring to the season when the changes take place. The U.S. government initially started Daylight Saving Time during World War I to save energy for wartime production. The federal government enacted Daylight Saving Time as a permanent change in 1966. Starting in 2007, the government extended the time period by four weeks as a means to save energy through longer daylight hours.