Time Zones in US Territories
The fifty states and the District of Columbia fit into six time zones — Eastern, Central, Mountain, Pacific, Alaska, and Hawaii-Aleutian. The US territories spread the picture further. Two of them sit east of the mainland, three sit far west in the Pacific, and one of those sits on the other side of the International Date Line. Together they push the United States across eleven hours of clock time at any given moment.
This page covers all five inhabited territories, plus a brief note on the small uninhabited possessions. Each entry lists the zone name, the UTC offset, and whether the territory observes daylight saving time.
Quick comparison
When New York is at noon Eastern Standard Time on a winter day, the rough local times in the territories are:
- Puerto Rico — 1:00 p.m.
- US Virgin Islands — 1:00 p.m.
- Guam — 3:00 a.m. the next day
- Northern Mariana Islands — 3:00 a.m. the next day
- American Samoa — 6:00 a.m. the same day
The pattern shifts in summer because the mainland switches to daylight time but the territories do not — so the offsets relative to Eastern, Central, Pacific, and Hawaii change by one hour for half the year.
The Caribbean territories
Puerto Rico
UTC−4 year-round (Atlantic Standard Time, AST)Puerto Rico is on Atlantic Standard Time, the zone between Eastern and the mid-Atlantic Ocean. It does not observe daylight saving time, which means it shares wall-clock time with mainland Eastern Daylight Time during the DST months (mid-March through early November), and runs one hour ahead of mainland Eastern Standard Time during winter.
For people coordinating with offices in New York, Atlanta, or Miami, the practical takeaway is that Puerto Rico's offset relative to the mainland changes twice a year, even though Puerto Rico's clocks never move. In winter, San Juan is one hour ahead of New York. In summer, San Juan and New York are on the same clock.
US Virgin Islands
UTC−4 year-round (Atlantic Standard Time, AST)St. Thomas, St. John, and St. Croix follow the same rule as Puerto Rico: Atlantic Standard Time, no DST. Anyone working between the Virgin Islands and the mainland sees the same seasonal one-hour shuffle described above. The Virgin Islands share their wall clock with much of the eastern Caribbean, including the British Virgin Islands and Dominica.
The Pacific territories
Guam
UTC+10 year-round (Chamorro Standard Time, ChST)Guam is on Chamorro Standard Time, named after the indigenous Chamorro people of the Mariana Islands. It does not observe daylight saving time. Guam is 14 hours ahead of New York in winter (EST), and 14 hours ahead of New York in summer becomes 13 hours during EDT, because the mainland moves forward and Guam does not.
Because Guam is on the same side of the dateline as the United States, the date "wraps" as you would expect for a place far west of the mainland: when it is Wednesday afternoon on the East Coast, it is already Thursday morning on Guam.
Northern Mariana Islands
UTC+10 year-round (Chamorro Standard Time, ChST)The Commonwealth of the Northern Mariana Islands — including Saipan, Tinian, and Rota — shares a zone with Guam. The rule is the same: UTC+10, no DST. Practically, anyone working between Saipan and Honolulu deals with a 20-hour clock difference (Honolulu is UTC−10, Saipan is UTC+10), or 19 hours during Aleutian DST.
American Samoa
UTC−11 year-round (Samoa Standard Time, SST)American Samoa sits in the South Pacific at UTC−11. It does not observe daylight saving time. American Samoa is one of the last places on Earth to enter each calendar day, along with a small number of uninhabited US Pacific possessions.
The neighbouring independent country of Samoa (formerly Western Samoa) chose to move from UTC−11 to UTC+13 in 2011, which means it is now on the other side of the International Date Line from American Samoa. The two places are about 100 kilometres apart but a full 24 hours apart on the calendar.
The uninhabited US possessions
Beyond the five inhabited territories, the United States administers several uninhabited islands in the Pacific and Caribbean. For completeness:
- Wake Island uses UTC+12 (Wake Island Time), with no DST.
- Howland Island and Baker Island, in the central Pacific, are uninhabited and assigned to UTC−12. They are the last places on the planet to see any given calendar date.
- Midway Atoll uses UTC−11, the same offset as American Samoa.
- Johnston Atoll uses UTC−10, the same as Hawaii.
- Navassa Island in the Caribbean is administered under Eastern Time conventions when used at all.
These are unlikely to come up in everyday scheduling but matter for navigation, weather reporting, and maritime law.
How territory time relates to mainland zones
A practical heads-up for anyone scheduling across the mainland and the territories:
- Atlantic Standard Time (Puerto Rico, USVI) is one hour ahead of Eastern Standard Time and the same as Eastern Daylight Time. Half the year, the offset to the mainland changes — Puerto Rico's clocks don't, but the mainland's do.
- Chamorro Standard Time (Guam, NMI) is closer in wall-clock terms to Tokyo and Seoul than to Honolulu. It does not switch with the seasons.
- Samoa Standard Time (American Samoa) is one hour behind Hawaii. The same applies year-round because neither place observes DST.
Why the territories don't observe DST
The federal Uniform Time Act of 1966 allows territories to opt out of DST in the same way states can. All inhabited territories have opted out, primarily because they sit at low latitudes where day length varies only modestly between summer and winter. In Puerto Rico, for example, the longest day of the year is only about an hour and a half longer than the shortest. The energy and lifestyle benefits that originally motivated DST in higher-latitude states are much smaller closer to the equator.
Use the converter
The on-site time converter covers all six mainland zones. For a quick check involving Puerto Rico or the Virgin Islands, treat them as "Eastern Time during summer, one hour ahead of Eastern Time during winter". For Guam and the Northern Marianas, treat them as Hawaii + 20 hours, or one calendar day ahead of the mainland. For American Samoa, treat as Hawaii − 1 hour.
For more on the abbreviations used here (AST, ChST, SST), see the abbreviations guide. For the historical reasons behind the territories falling outside the six-zone mainland system, see the history page.