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Daylight Saving Time
Image of partial clock face.

Benjamin Franklin is credited with the concept of Daylight Saving Time. The basic idea is to make the best use of daylight hours by shifting the clock forward in the spring and backward in the fall. Daylight Saving Time has been in use throughout much of the United States, Canada and Europe since World War I. In 1966, President Lyndon Johnson signed an act into law whereby Daylight Saving Time begins on the last Sunday of April and ends on the last Sunday of October each year. However, any state can opt out of Daylight Saving Time by passing a law.

Hawaii does not observe Daylight Saving Time and neither does Arizona (although the Navajo Nation, in northeastern Arizona, does). For many years, most of Indiana did not observe Daylight Saving Time with the exception of 10 counties. Beginning in 2006, all of Indiana now observes Daylight Saving Time.

US Federal law was amended in 1986 to begin Daylight Saving Time on the first Sunday in April:

  • Daylight Saving Time begins at 2 a.m. on the first Sunday of April
  • Daylight Saving Time ends at 2 a.m. on the last Sunday of October

In 2005, President Bush signed into law a new energy policy bill that would extend Daylight Saving Time by 4 weeks beginning in 2007:

  • Daylight Saving Time begins at 2 a.m. on the second Sunday of March
  • Daylight Saving Time ends at 2 a.m. on the first Sunday of November

The corresponding time zones in Canada also switch to Daylight Saving Time on the same dates. However, some regions of in British Columbia and Saskatchewan do not use Daylight Saving Time. They include: Charlie Lake, Creston (East Kootenays), Dawson Creek, Fort St. John, and Taylor (all in British Columbia), and most of Saskatchewan (except Creighton and Denare Beach).

In Europe, Daylight Saving Time is referred to as Summer Time. Throughout most of western Europe (including members of the European Community (EC)):

  • Summer Time (Daylight Saving) Begins at 1 a.m. GMT on the last Sunday of March
  • Summer Time (Daylight Saving) Ends at 1 a.m. GMT on the last Sunday of October

Written by Fred Espenak

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Last Updated: 24 January 2011

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Last Updated: 24 Jan 2011