ANSWER
In 1784 Benjamin Franklin first proposed what we now call Daylight Saving Time, but most people thought he was kidding.
The first serious proposal came from Englishman William Willett in 1907. British Summer Time became law in Britain in 1916, one year after Willett's death.
Daylight Saving Time became law in the US during World War I as part of the Standard Time Act of 1918, but it was repealed the following year. It became law again from 1942 to 1945, during World War II. It was not addressed again at a federal level until the Uniform Time Act of 1966, which re-established a national Daylight Saving Time. The law was amended in 1986, giving us Daylight Saving Time as we know it today.
(Daylight Saving Time is not observed in Arizona, Hawaii, and most of Indiana.)
WHO GOT IT RIGHT: Lee Lewis, Allan Christensen, and Robin Campbell.
