Daylight Savings Time

History of Daylight Saving Time in the U.S.

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 passage of The Standard Time Act on March 19, 1918. The Standard Time Act also established Daylight Saving Time, which was a contentious idea at the 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 Daylight saving time was repealed in 1919, but standard time in time zones remained in law.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 9 February 1942 to 30 September 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 Saving Time in the U.S. but allowed for local exemptions from its observance. The Uniform Time Act provided that Daylight Saving 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 Saving Time. In 1974, Daylight Saving Time began on 6 January and in 1975 it began on 23 February. After those two years the starting date reverted to the last Sunday in April. In 1986, a law was passed that shifted the starting date of Daylight Saving Time to the first Sunday in April, beginning in 1987. The ending date of Daylight Saving 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 Saving Time starts on the second Sunday in March and ends on the first Sunday in November.

For a very readable account of the history of standard and daylight time in the U.S., see

Ian R. Bartky and Elizabeth Harrison: "Standard and Daylight-saving Time", Scientific American, May 1979 (Vol. 240, No. 5), pp. 46-53.

Source: https://aa.usno.navy.mil/faq/daylight_time