Daylight saving time in the United States was first observed in 1918. Most areas of the United States currently observe daylight saving time, with the exceptions being the states of Arizona and Hawaii along with Puerto Rico, American Samoa, Guam, Northern Mariana Islands, and the United States Virgin Islands.
From 1987 to 2006, daylight saving time in the United States began on the first Sunday of April and ended on the last Sunday of October. The time was adjusted at 2:00 AM (0200) local time (as it still is done now).
Since 2007, daylight saving time starts on the second Sunday of March and ends on the first Sunday of November, with all time changes taking place at 2:00 AM (0200) local time. In 2011, daylight saving time began on March 13 and ended on November 6; in 2012, it will begin on March 11 and end on November 4; in 2013, it will begin on March 10 and end on November.
From Wikipedia, the free encyclopedia