Daylight Saving Time, for the U.S. and its territories, is NOT observed in Hawaii, American Samoa, Guam, Puerto Rico, the Virgin Islands and the state of Arizona (not the Navajo Indian Reservation, which does observe DST). Navajo Nation participates in the Daylight Saving Time policy, due to its large size and location in three states.
Official Reference: UNITED STATES CODE, TITLE 15 - COMMERCE AND TRADE, CHAPTER 6 - WEIGHTS AND MEASURES AND STANDARD TIME, SUBCHAPTER IX - STANDARD TIME
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