Man with clocks

Love it or hate, every year, the majority of Americans observe Daylight Saving Time (sometimes mistakenly called "Daylight Savings Time") - the practice of moving clocks forward by one hour during summer months so that daylight lasts longer into the evening.

In the United States, DST starts on the second Sunday in March - in this case, March 14- when people move their clocks forward an hour at 2 a.m. local standard time. Daylight saving time ends on the first Sunday in November - November 1 of this year -  when clocks are moved back an hour at 2 a.m. local daylight time.

Not everyone in the United States springs forward and falls back.

Hawaii and Arizona—with the exception of the state’s Navajo Nation—do not observe daylight saving time, and the U.S. territories of American Samoa, Guam, Puerto Rico, the Virgin Islands, and the Northern Mariana Islands also remain on standard time year-round. Some Amish communities also choose not to participate in daylight saving time. (Around the world, only about one-quarter of the world’s population, in approximately 70 countries, observe daylight saving. Since their daylight hours don’t vary much from season to season, countries closer to the equator have little need to deviate from standard time.)

While most of North America and Europe follow the custom, the majority of countries elsewhere do not - in fact, fewer than 40 percent of the world's countries observe daylight saving time, according to

History of Daylight Saving Time

American statesman and inventor Benjamin Franklin first came up with the idea to reset clocks in the summer months as a way to conserve energy by taking advantage of the extra evening daylight. He shared this idea in a well-known letter, titled "An Economical Project for Diminishing the Cost of Light", sent to the editor of The Journal of Paris in 1784. However, it wasn't until more than a century later that DST was actually enacted.

In May 1916, Germany established DST as a way to conserve fuel during World War I, according to Weeks later, the United Kingdom followed suit and introduced "summertime," and in 1918, the United States adopted daylight saving time.

DST was abolished shortly after WWI after farmers objected to it, as they lost an hour of morning light. However, some cities, including Pittsburgh, Boston, and New York, continued to use it. At the start of WWII, on Feb. 9h, President Franklin Roosevelt re-established daylight saving time year-round, calling it "War Time."

In 1966, Congress enacted the Uniform Time Act, meaning that any state observing DST had to follow a uniform protocol throughout the state in which daylight saving time would begin on the first Sunday of April and end on the last Sunday of October, according to LiveScience. The current schedule was introduced in 2007 and follows the Energy Policy Act of 2005, which extended the period by about one month.

Today, Hawaii and Arizona do not observe daylight saving time, and the U.S. territories of American Samoa, Guam, Puerto Rico, the Virgin Islands, and the Northern Mariana Islands also remain on standard time year-round.

Why do we change time and move the clock forward?

A primary reason for observing DST is to take advantage of the natural daylight in the evenings.

LiveScience puts it this way: "Days start to get longer as Earth moves from the winter season to spring and summer, with the longest day of the year on the summer solstice. That's because during the summer, Earth, which revolves around its axis at an angle, is tilted directly toward the sun (at least it's top half)."

Others say that DST conserves energy by extending summer daylight later into the evening. However, a 2008 U.S. Department of Energy study reported that daylight saving time reduces annual energy use by about 0.03%, another study from the University of California-Santa Barbara found it might even increase energy consumption.

Nevertheless, proponents of DST say it minimizes traffic accidents, saves energy, boosts tourism, and prompts more people to exercise outdoors.  

Stanton Hadley, a senior researcher at Oak Ridge National Laboratory who helped prepare a report to Congress on extended daylight saving time in 2007, told Live Science: "In the vast scheme of things, the energy saving is not the big driver," he said. "It's people wanting to take advantage of that light time in the evening."