The Uniform Time Act of 1966 is signed by President Lyndon Johnson on April 14, 1966. The act mandated standard time within the established time zones and provided for Day Light Savings time (DST).
Clocks would be advanced one hour beginning at 2:00 a.m. on the last Sunday in April (Currently the second Sunday of March) and turned back one hour at 2:00 a.m. on the last Sunday in October (currently the first Sunday in November). States were allowed to exempt themselves from DST as long as the entire state did so. If a state chose to observe DST, the time changes were required to begin and end on the established dates. As of 2026, DST is not observed in the U.S. States of Hawaii, most of Arizona and the U.S. territories of American Samoa, Guam, the Northern Mariana Islands, Puerto Rico, and the U.S. Virgin Islands,
