<P> During World War II , Congress enacted the War Time Act ( 56 Stat. 9 ) on January 20 , 1942 . Year - round DST was reinstated in the United States on February 9 , 1942 , again as a wartime measure to conserve energy resources . This remained in effect until after the end of the war . The Amendment to the War Time Act ( 59 Stat. 537 ) , enacted September 25 , 1945 , ended DST as of September 30 , 1945 . During this period , the official designation War Time was used for year - round DST . For example , Eastern War Time ( EWT ) would be the equivalent of Eastern Daylight Time during this period . </P>
<P> During World War II , Congress enacted the War Time Act ( 56 Stat. 9 ) on January 20 , 1942 . Year - round DST was reinstated in the United States on February 9 , 1942 , again as a wartime measure to conserve energy resources . This remained in effect until after the end of the war . The Amendment to the War Time Act ( 59 Stat. 537 ) , enacted September 25 , 1945 , ended DST as of September 30 , 1945 . During this period , the official designation War Time was used for year - round DST . For example , Eastern War Time ( EWT ) would be the equivalent of Eastern Daylight Time during this period . </P>
when did the usa start using daylight savings time
when did the usa start using daylight savings time
January 20 , 1942
January 20 , 1942