US States Time Zones

How U.S. state time zones are decided

Time-zone boundaries inside the United States are defined by the U.S. Department of Transportation under the Uniform Time Act. Boundaries generally follow state lines, but where a state has historic, economic, or geographic ties on both sides of a meridian, the boundary cuts through the state along county lines. A state can petition the DOT to change the boundary; this happens occasionally as commerce shifts.

Whether a state observes daylight saving time is a separate decision: a state can stay on standard time year-round (Hawaii and most of Arizona), but it cannot pick its own DST start and end dates. For the full DST mechanics, see the daylight saving time guide.

Which US states are in the Eastern and Central time zones?

This is the most common state-and-zone question, and the honest answer is that it takes three lists, not two, because a dozen states sit in both.

Entirely Eastern Time: Connecticut, Delaware, Georgia, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Vermont, Virginia and West Virginia — plus the District of Columbia.

Entirely Central Time: Alabama, Arkansas, Illinois, Iowa, Louisiana, Minnesota, Mississippi, Missouri, Oklahoma and Wisconsin.

Split between Eastern and Central: Florida, Indiana, Kentucky, Michigan and Tennessee. In each of these the boundary runs along county lines, so the state name alone is not enough to answer the question — you need the county or the nearest city. Florida's Panhandle, western Kentucky, Michigan's far western Upper Peninsula, a handful of Indiana counties near Chicago and Evansville, and Middle and West Tennessee are all on Central; the rest of each state is on Eastern.

Together, the Eastern and Central zones cover roughly four out of every five people in the United States. The remaining states fall into the Mountain, Pacific, Alaska and Hawaii–Aleutian zones, all listed in the table below.

US time zones by state — full A–Z list

All 50 states and the District of Columbia, with the zone (or zones), the standard and daylight abbreviations, and whether daylight saving time is observed.

A note on Arizona: it sits in the Mountain zone but stays on MST all year, so from March to November its clock reads the same as Pacific Time in California. The Navajo Nation, which extends into north-eastern Arizona, does observe daylight saving time. See the daylight saving time guide for the dates and the reasoning.

Single-zone states

The states (and the District of Columbia) that sit entirely in one zone:

Eastern Time

Connecticut, Delaware, District of Columbia, Georgia, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Vermont, Virginia, West Virginia.

Central Time

Alabama, Arkansas, Illinois, Iowa, Louisiana, Minnesota, Mississippi, Missouri, Oklahoma, Wisconsin.

Mountain Time

Colorado, Montana, New Mexico, Utah, Wyoming. Arizona is also in the Mountain zone but does not observe DST, so its clock matches Pacific Time for the half of the year that DST is in effect — except on the Navajo Nation, which does observe DST.

Pacific Time

California, Nevada, Washington.

Alaska Time

Most of Alaska. The westernmost Aleutian Islands are in the Hawaii–Aleutian zone — see below.

Hawaii–Aleutian Time

Hawaii uses this zone and does not observe DST. The portion of Alaska's Aleutian Islands west of about 169° 30′ W also sits here and does observe DST.

States that span two zones

Roughly a dozen states straddle a zone boundary. The list below names the two zones and identifies, in plain terms, which side of the state holds which.

The Arizona / Navajo Nation special case

Arizona is the most-asked-about case. The state opted out of daylight saving time in 1968. The Navajo Nation, which extends across parts of Arizona, New Mexico, and Utah, observes DST throughout. That creates a small geographic puzzle: from March to November, driving from Tuba City (Navajo Nation) to Flagstaff (Arizona, no DST) crosses an effective one-hour boundary, even though both are within the same state and even though Arizona's "standard" zone is technically Mountain. The Hopi Reservation, surrounded by the Navajo Nation, follows Arizona's no-DST rule.

U.S. territories

• Puerto Rico and the U.S. Virgin Islands — Atlantic Standard Time (UTC-4), no DST. Year-round, this matches Eastern Daylight Time in summer and is one hour ahead of Eastern Standard Time in winter.
• Guam and the Northern Mariana Islands — Chamorro Standard Time (UTC+10), no DST.
• American Samoa — Samoa Standard Time (UTC-11), no DST.
• Wake Island — Wake Island Time (UTC+12), no DST.
• Baker Island, Howland Island — uninhabited, technically UTC-12.

Quick lookup tips

• If a state is split, the boundary almost always follows county lines. Local courthouses, school districts, and TV stations make excellent tie-breakers when you're not sure which side a small town is on.
• The IANA zone identifier is the safest way to be precise in writing or software. America/Detroit handles Michigan correctly even for the small set of counties on Central Time, because those counties have their own identifier (America/Menominee). The same is true for Indiana — there are several IANA zones inside the state.
• Don't assume "the state capital sets the zone." It usually does, but in Florida, Tennessee, and a couple of other states the capital and a major commercial city are on different sides of the line.

Related

To see the live time in every U.S. zone right now, head to the homepage. To convert a specific moment between any two zones, use the converter. For the practical scheduling implications of all this, see scheduling across U.S. time zones. For the abbreviations used in writing, the US time zone abbreviations reference covers them in one place, and the two most-confused pairs have pages of their own: EST vs EDT and PST vs PDT.