The United States spans six time zones across the contiguous 48 states, Alaska, and Hawaii — making it one of the most important countries to understand for international scheduling.
Eastern Time (ET) covers the most populous corridor: New York, Boston, Miami, Atlanta, Washington D.C., and Detroit. Standard time is UTC−5 (EST); daylight time is UTC−4 (EDT). Central Time (CT) covers Chicago, Houston, Dallas, Minneapolis, and New Orleans — UTC−6 (CST) and UTC−5 (CDT). Mountain Time (MT) covers Denver, Phoenix, Salt Lake City, and Albuquerque — UTC−7 (MST) and UTC−6 (MDT). Pacific Time (PT) covers Los Angeles, San Francisco, Seattle, Las Vegas, and Portland — UTC−8 (PST) and UTC−7 (PDT).
Alaska Time (AKT) covers Anchorage and Fairbanks — UTC−9 (AKST) / UTC−8 (AKDT). Hawaii-Aleutian Time (HST) covers Honolulu at UTC−10 with no daylight saving time ever.
DST in 2025: clocks spring forward on Sunday 9 March and fall back on Sunday 2 November in all states except Arizona (stays on MST, UTC−7, year-round) and Hawaii. The Navajo Nation within Arizona does observe DST. Indiana formerly had complex rules but now observes Eastern Time statewide.
Key inter-city gaps during standard time: New York to Chicago = 1 hour. New York to Denver = 2 hours. New York to Los Angeles = 3 hours. New York to Anchorage = 4 hours. New York to Honolulu = 5 hours. During EDT, the New York–London difference narrows to 4 hours.
