Karin Stanton | Hawaii 24/7 Contributing Editor

Most of the rest of the U.S. will be springing forward tonight as daylight savings time begins. Of course, Puerto Rico, America Samoa, U.S. Virgin Islands, Arizona and Hawaii – along with Chile this year – don’t observe DST.

Daylight saving time (DST) begins each year on the second Sunday in March at 2 a.m. (local time). Clocks are moved ahead one hour when DST goes into effect.

That means the West Coast is plus 3 hours; the East Coast is plus 6 hours from Hawaii time.

Everyone who springs forward with be falling back on Nov. 7.

Although standard time in time zones was instituted in the U.S. and Canada by the railroads in 1883, it was not established in U.S. law until the Act of March 19, 1918.

The act also established daylight saving time. Daylight saving time was repealed in 1919, but standard time in time zones remained in law. Daylight time became a local matter.

It was re-established nationally early in World War II, and was continuously observed from Feb. 9, 1942 to Sept. 30 1945. After the war, its use varied among states and localities.

The Uniform Time Act of 1966 provided standardization in the dates of beginning and end of daylight time in the U.S. but allowed for local exemptions from its observance. The act provided that daylight time begin on the last Sunday in April and end on the last Sunday in October, with the changeover to occur at 2 a.m. local time.

During the “energy crisis” years, Congress enacted earlier starting dates for daylight time. In 1974, daylight time began Jan. 6 and in 1975 it began Feb. 23. After those two years the starting date reverted back to the last Sunday in April.

In 1986, a law was passed that shifted the starting date of daylight time to the first Sunday in April, beginning in 1987. The ending date of daylight time was not subject to such changes, and remained the last Sunday in October. The Energy Policy Act of 2005 changed both the starting and ending dates.

Beginning in 2007, daylight time starts on the second Sunday in March and ends on the first Sunday in November.

— Find out more:
www.nist.gov/physlab/div847/localtime.cfm#who
http://geography.about.com/od/findmaps/ig/Country-Maps/Time-Zone-Map.htm