When Does Daylight Saving Time Start?

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During daylight saving time clocks are set ahead by one hour in most areas of the United States. Daylight saving time begins on the second Sunday of March each year. In 2018 daylight saving time begins on March 11 at 2 a.m. and ends on Nov. 4 at 2 a.m.

The History of Daylight Saving Time
The first use of daylight saving time was in Port Arthur, Ontario, Canada, in 1908. After spreading through Canada, it became popular in parts of Europe. The idea caught on globally after the government of Germany implemented the time change in 1916 during World War I. Hoping to use the extra hour of daylight in the evenings to conserve fuel needed for the war, much of Europe and the United States followed suit, setting their clocks forward one hour in the spring of 1916, and setting them back again in the fall of 1917.

Why Do We Have Daylight Saving Time?
As the seasons change from spring to summer, daylight hours get longer until the summer solstice. Countries that observe daylight saving time derive an extra benefit from these additional hours of sunlight during the spring, summer and early fall months. Areas closer to the poles see the most dramatic increase in sunlight due to daylight saving time, because the ratio of daylight to darkness hours changes the most with the seasons in these regions.

Daylight saving time was originally put in place in order to save energy. However researchers have found little evidence that daylight saving time has a large impact on energy use or conservation. While the extra hour of daylight in the evenings may save the need to use electric lighting in homes, the energy efficiency of electric lighting today offsets the total amount of conserved energy.

Who Observes Daylight Saving Time?
With the exception of the states of Hawaii and Arizona, the U.S. observes daylight saving time. Canada observes the time change with a few exceptions. Several areas of British Columbia and Saskatchewan choose not to observe the time change. The U.S. and Canada observe the time change on the same dates each year.

The majority of countries in Europe observe a form of daylight saving time called "summer time." Summer time begins on the last Sunday in March and ends on the last Sunday in October.

In the Southern Hemisphere daylight saving time is observed by New Zealand, Australia, and many countries in South America and southern Africa.

When to Change the Clocks
While the specific dates vary each year, the guidelines for changing clocks to reflect daylight saving time remain constant. Clocks should be moved forward one hour at 2 a.m. on the second Sunday of March, and moved backward one hour at 2 a.m. on the first Sunday of November. It may be helpful to remember how to change the clocks each year using the phrases "spring forward" and "fall back."

Because daylight saving time changes occur in the middle of the night, some individuals choose to set their clocks forward or back before going to sleep on the night before the changes go into effect.