ANSI - American National Standards Institute
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“Spring” Ahead: Daylight Saving Time begins April 3


New York, Apr 01, 2005

Daylight Saving Time is a change in standard time that begins each year at 2 a.m. on the first Sunday of April in most of the United States and its territories. This Sunday, April 3, we will set our clocks forward one hour ahead of standard time (DST is not observed in Hawaii, American Samoa, Guam, Puerto Rico, the Virgin Islands, most of the Eastern Time Zone portion of the State of Indiana, and the state of Arizona1). Standard Time begins again annually in the U.S. at 2 a.m. on the last Sunday of October.

The purpose of Daylight Saving Time is conservation of energy. By shifting daylight from morning to evening, less energy is consumed during waking hours. It was originally instituted in the United States during World War I to save energy for war production by taking advantage of the later hours of daylight between April and October; this same practice was implemented during World War II. In 1966, Congress passed the Uniform Time Act which standardized the length of Daylight Saving Time, but left it up to the states to decide if they would observe.

There appear to be other benefits to DST as well. According to David Prerau, the author of "Seize the Daylight: The Curious and Contentious Story of Daylight Saving Time," studies in many countries have found that Daylight Saving Time not only curbs energy consumption but also reduces traffic fatalities. Generally, more commuters are on the road in the evening than in the morning, and with more daylight, visibility is increased. It is even posited that incidences of crime where darkness is a factor decrease with more daylight hours.

Here are a few more interesting facts about Daylight Saving Time:

  • About 70 other nations also observe a daylight saving time:

    In 1996 the European Union (EU) standardized an EU-wide "summertime period," which extends from the last Sunday in March through the last Sunday in October.

    During the summer, Russia's clocks are two hours ahead of standard time.

    The only major industrialized country not to have introduced daylight saving is Japan.

  • Following the 1973 Arab Oil Embargo, Congress put most of the nation on extended Daylight Saving Time in hopes of saving additional energy. In 1974, DST lasted ten months and in 1975 lasted for eight months.

  • Daylight Saving Time in the U.S. always ends a few days before Halloween, and there have been numerous proposals in Congress for legislation to extend DST to Halloween. Children’s pedestrian deaths are four times higher on Halloween than on any other night of the year – extending DST would provide trick-or-treaters with more light and therefore more safety from moving vehicles.

  • Consumers are encouraged to change the batteries in their smoke detectors when they change their clocks, because it is an easy habit to remember.

See related article: Clocks Roll Back on October 31 as "Standard" Time Begins Again


[1]The Navajo Indian Reservation in Arizona does observe DST.

 Homeland Defense and Security Standardization Collaborative