Video: 'Daylight Saving Time Explained'

(Sunday, March 19, 1918) — President Woodrow Wilson today signed the first law establishing daylight saving time in the United States, with clocks to be moved forward one hour from the last Sunday in March to the last Sunday in October.

The Standard Time Act of 1918, also known as the Calder Act, was passed in an effort to conserve fuel during World War I. It was repealed after the war on August 20, 1919, over President Woodrow Wilson’s veto.

Daylight Saving Time became a local option and was observed in some states, except during World War II when President Franklin Roosevelt instituted year-round DST.

The Uniform Time Act of 1966 established the system of uniform Daylight Saving Time throughout the U.S.