What time zone is Puerto Rico in?

Atlantic Standard Time, four hours behind Coordinated Universal Time. Puerto Rico does not observe daylight saving, so it runs one hour ahead of New York during the winter and exactly level with New York from March to November, when the mainland is on Eastern Daylight Time.

How far ahead is Guam of the United States mainland?

Fifteen hours ahead of Eastern Standard Time, on Chamorro Standard Time at UTC plus ten. Because Guam lies west of the International Date Line, it is usually on the next calendar day relative to the mainland, so Monday morning there is Sunday evening in Washington.

Do US territories change their clocks for daylight saving?

None of them does. Puerto Rico, the US Virgin Islands, Guam, the Northern Mariana Islands and American Samoa all stay on standard time all year. They sit at low latitudes where day length barely changes with the seasons, so shifting the clock would gain almost no evening daylight.

What time zone is American Samoa in?

Samoa Standard Time at UTC minus eleven, one hour behind Hawaii and six hours behind New York in winter. The neighbouring independent state of Samoa moved to the western side of the International Date Line in 2011, so the two are now about a day apart.

US Territories Time Explained

The fifty states cover six standard zones, but the country does not stop there. Working out US territories time means adding zones that sit beyond both ends of the mainland range: one an hour ahead of New York, and others so far west that they are on tomorrow's date while Washington is still on today's. None of them changes its clocks.

This article covers time in the US territories in turn: Puerto Rico and the US Virgin Islands on Atlantic Standard Time, Guam and the Northern Mariana Islands on Chamorro Standard Time, American Samoa in the south Pacific, and the remote islands beyond. To compare the far ends of the country at a glance, open the Alaska and Hawaii clock.

US Territories Time: Which Zones Are There?

Puerto Rico and the US Virgin Islands keep Atlantic Standard Time, UTC minus four. Guam and the Northern Mariana Islands keep Chamorro Standard Time, UTC plus ten. American Samoa keeps UTC minus eleven. None of these observes daylight saving time.

Because the territories hold still while the mainland shifts, their relationship with the states changes twice a year. That is the single most useful thing to remember about US territories time, and the source of most scheduling errors.

Puerto Rico and the US Virgin Islands

Both sit on Atlantic Standard Time at UTC minus four, one hour ahead of Eastern Standard Time. San Juan, Charlotte Amalie and Christiansted therefore run an hour ahead of New York through the winter.

In summer the gap closes. When the mainland moves to Eastern Daylight Time, also UTC minus four, Puerto Rico and the East Coast read exactly the same clock from March to November. That makes Puerto Rico the simplest corner of US territories time to work with for eight months of the year and a mildly confusing one for the other four, since a habit formed in July is wrong in January. The Eastern Time clock is the natural reference point for anyone comparing. Atlantic Standard Time is shared with several independent Caribbean nations and with the Atlantic provinces of Canada, though the Canadian side does observe daylight saving and the territories do not.

Guam and the Northern Mariana Islands

Guam and the Commonwealth of the Northern Mariana Islands keep Chamorro Standard Time, UTC plus ten, named for the indigenous people of the Marianas. This puts them fifteen hours ahead of Eastern Standard Time and on the other side of the International Date Line from the mainland, which is US territories time at its most extreme.

The practical effect is that Guam is almost always on the next calendar day relative to Washington. A Monday morning in Hagatna is a Sunday evening on the East Coast, which is why the islands are sometimes described as the place where America's day begins. For anyone coordinating work across this span, the overlap with mainland office hours is minimal, and the usual advice about calling across US time zones becomes a matter of choosing which side takes the awkward hour.

American Samoa and the Remote Islands

American Samoa sits at UTC minus eleven, one hour behind Hawaii and six hours behind Eastern Standard Time. Pago Pago is therefore among the last inhabited places in the world to see a given date out.

It is worth noting that neighbouring Samoa, an independent country, moved to the other side of the International Date Line in 2011 to align with Australia and New Zealand, so the two Samoas are now around a day apart despite being a short flight from one another. Beyond the inhabited territories, the United States administers several minor islands with their own offsets, including Wake Island in the far western Pacific and Midway Atoll, which keeps the same offset as American Samoa. These are staffed rather than settled, but they extend US territories time across almost the full width of the world's clock.

Do Any US Territories Observe Daylight Saving?

No. Puerto Rico, the US Virgin Islands, Guam, the Northern Mariana Islands and American Samoa all remain on standard time throughout the year, so their offsets from Coordinated Universal Time never change. That single rule governs all US territories time.

The reason is the same one Hawaii gives: all five lie at low latitudes where the length of the day varies little between seasons, so moving the clock would buy almost no extra evening daylight. Hawaii's identical position is covered in states that don't observe daylight saving. The consequence is that all comparisons with the mainland need to be made twice, once for winter and once for summer.

The legal position differs from a state's as well. The Uniform Time Act of 1966 built the national schedule around the states and let each of them opt out by its own law, which is how Arizona and Hawaii came to stand still. The territories were never brought inside that schedule in the same way, so their standard time is fixed rather than exempted, and proposals such as the Sunshine Protection Act, which would make daylight time permanent on the mainland, would leave them untouched.

US Territories Time at a Glance

Here is every inhabited US territory with its zone and its distance from the East Coast in winter, when the mainland is on standard time.

Puerto Rico: Atlantic Standard Time, UTC minus four. One hour ahead of New York in winter, level with it in summer.
US Virgin Islands: Atlantic Standard Time, UTC minus four. Identical to Puerto Rico in every respect.
Guam: Chamorro Standard Time, UTC plus ten. Fifteen hours ahead of New York in winter, and on the following date.
Northern Mariana Islands: Chamorro Standard Time, UTC plus ten. Shares Guam's clock exactly, including Saipan and Tinian.
American Samoa: UTC minus eleven. Six hours behind New York in winter and one hour behind Honolulu.

Set against the states, these zones stretch the country's clock across a span of twenty-one hours. The mainland portion of that range is described in US time zones explained.

Two comparisons make the span easier to picture. When the working day begins in Guam it is still the previous evening in Washington, and when the working day ends in Pago Pago the East Coast is already well into the night. Between those extremes sit Alaska and Hawaii, the two states that stretch the country furthest west, and Puerto Rico, which is the only inhabited part of the United States lying east of the Eastern zone. A federal agency with offices in all of them can never find an hour when every desk is occupied.

Conclusion

US territories time comes down to four offsets and one constant rule. Puerto Rico and the US Virgin Islands keep Atlantic Standard Time at UTC minus four; Guam and the Northern Mariana Islands keep Chamorro Standard Time at UTC plus ten, a day ahead of the mainland; American Samoa sits at UTC minus eleven. None observes daylight saving, so each moves an hour closer to or further from the states every March and November without touching its own clock. Compare the far edges of the country on the Alaska and Hawaii clock, or see every zone at ustime.now.

US Territories Time: Atlantic, Chamorro and Samoa Zones