Clocks in 48 states will "fall back" this weekend as most of the United States returns to Standard Time.
Arizona, Hawaii and the U.S. territories of Puerto Rico, Virgin Islands, Guam and American Samoa never changed their clocks in the spring, so they won't touch their clocks this weekend, either.
The idea of changing the clocks twice a year first came about to provide more daylight during the evening hours in the spring and summer and was later implemented as a way to try and conserve energy.
Since then, studies have gone back and forth as to whether any more or less energy is used.
No state is required to participate in Daylight Saving Time, but the Uniform Time Act of 1966 set a specific time and date to change the clocks. As of August 2005, most of the country springs forward the second Sunday in March and falls back the first Sunday in November.