Germany was the first to adopt daylight saving time on May 1, 1916, during World War I as a way to conserve fuel. The rest of Europe followed soon after.
The United States didn’t adopt daylight saving time until March 19, 1918. It was unpopular and abolished after World War I.
On Feb. 9 ,1942, Franklin Roosevelt instituted a year-round daylight saving time, which he called “war time.” This lasted until Sept. 30, 1945.
Daylight saving time didn’t become standard in the US until the passage of the Uniform Time Act of 1966, which mandated standard time across the country within established time zones. It stated that clocks would advance one hour at 2 a.m. on the last Sunday in April and turn back one hour at 2 a.m. on the last Sunday in October.
States could still exempt themselves from daylight saving time, as long as the entire state did so. In the 1970s, due to the 1973 oil embargo, Congress enacted a trial period of year-round daylight saving time from January 1974 to April 1975 in order to conserve energy.