Daylight Saving Time was first implemented in the US with the Standard Time Act of 1918, a wartime measure for seven months during World War I in the interest of adding more daylight hours to conserve energy resources. Year-round DST, or “War Time”, was implemented again during World War II.
Arizona and Hawaii have opted out of the practice.
Note: Europe last ended DST last Sunday. So as of the Sunday, the time zones between the US and Europe will come back to their normal spread.
Related reading:
Daylight Saving Time History & Law
Daylight Saving Time (Wikipedia)
