The Six US Time Zones
The United States has six primary time zones, each with a standard time offset and a separate daylight saving time offset:
- Eastern Time (ET): EST = UTC−5, EDT = UTC−4. States: NY, FL, OH, PA, GA, NC, and more.
- Central Time (CT): CST = UTC−6, CDT = UTC−5. States: TX, IL, MN, MO, WI, and more.
- Mountain Time (MT): MST = UTC−7, MDT = UTC−6. States: CO, AZ (most), UT, NM, WY, and more.
- Pacific Time (PT): PST = UTC−8, PDT = UTC−7. States: CA, WA, OR, NV.
- Alaska Time (AKT): AKST = UTC−9, AKDT = UTC−8. Covers most of Alaska.
- Hawaii-Aleutian Time (HAT): HST = UTC−10 (no DST for Hawaii), HAST = UTC−10, HADT = UTC−9 (Aleutian Islands observe DST).
Special Cases
- Arizona: Most of the state uses MST (UTC−7) year-round with no DST. The Navajo Nation within Arizona does observe DST (MDT = UTC−6).
- Indiana: The state standardized to Eastern Time in 2006 after years of varying DST policies by county.
- Navajo Nation: Spans Arizona, Utah, and New Mexico. Only the Arizona portion observes DST.
Daylight Saving Time in the US
The US currently observes DST from the second Sunday in March (clocks spring forward 1 hour) to the first Sunday in November (clocks fall back 1 hour). The Sunshine Protection Act, passed by the US Senate in 2022, would make DST permanent, but as of 2025 it has not been enacted into law.
US Territories
US territories outside the 50 states use additional time zones:
- Puerto Rico and US Virgin Islands: UTC−4 (AST, no DST)
- Guam and Northern Mariana Islands: UTC+10 (ChST, no DST)
- American Samoa: UTC−11 (SST, no DST)
Scheduling Across the US
The difference between New York (ET) and Los Angeles (PT) is 3 hours. A meeting at 9 AM in New York is 6 AM in Los Angeles, which is why US East Coast offices often schedule afternoon meetings for cross-coast calls. Alaska adds another 1 hour behind Pacific, and Hawaii-Aleutian adds 2–3 hours more.