According to the NIST daylight saving time begins at 2am, Sunday, March 8th. Arizona’s still being a dick about it.
DST was formally introduced in the United States in 1918. Today, most of the country and its territories observe DST. However, DST is not observed in Hawaii, American Samoa, Guam, Puerto Rico, the Virgin Islands and the state of Arizona (with the exception of the Navajo Indian Reservation, which does observe DST).
Daylight saving time and time zones are regulated by the U. S. Department of Transportation, not by NIST.