Daylight saving time in the US

DST dates through 2030

Both changes happen at 2:00 AM local time in each zone, so the country switches in waves — Eastern first, Hawaii never.

Who doesn't change clocks

Hawaii and most of Arizona stay on standard time all year. The Navajo Nation within Arizona does observe DST; the Hopi Reservation inside it does not — creating a place where driving in a loop changes your clock twice.

US territories — Puerto Rico, Guam, American Samoa, and the US Virgin Islands — also skip DST.

Why DST exists — and why it may end

The US first used DST in 1918 as a wartime energy measure, made it year-round during World War II ("War Time"), and standardized the modern rules with the Uniform Time Act of 1966. The current March–November window dates from the Energy Policy Act of 2005, in effect since 2007.

Congress has repeatedly considered making daylight time permanent — the Sunshine Protection Act passed the Senate in 2022 but stalled in the House. Nineteen states have passed laws to adopt permanent DST if federal law ever allows it, including California and Florida. Until then, the twice-yearly change stands.

Practical effect on time differences: gaps between DST-observing zones never change, but Arizona effectively joins Pacific Time in summer, and Hawaii drifts from 5 to 6 hours behind Eastern.