Congress pushed ahead standard time for the United States by
one hour in each time zone, imposing daylight saving time—
called at the time “war time.”

Daylight saving time, suggested by President Roosevelt, was
imposed to conserve fuel and could be traced back to World
War I, when Congress imposed one standard time on the
United States to enable the country to better utilize resources,
following the European model.

The 1918 Standard Time Act was meant to be in effect for only
seven months of the year—and was discontinued nationally
after the war.

     
President Franklin D. Roosevelt (1882–1945)