What are the 6 US time zones in order?

From east to west: Eastern Standard Time (UTC-5), Central Standard Time (UTC-6), Mountain Standard Time (UTC-7), Pacific Standard Time (UTC-8), Alaska Standard Time (UTC-9), and Hawaii-Aleutian Standard Time (UTC-10). During Daylight Saving Time, each zone except Hawaii and most of Arizona shifts forward by one hour.

Which US states are split between two time zones?

Thirteen states are split across two time zones: Alaska, Florida, Idaho, Indiana, Kansas, Kentucky, Michigan, Nebraska, North Dakota, Oregon, South Dakota, Tennessee, and Texas. The split usually follows county lines that match historic transportation or trade ties to neighboring time zones.

Why does Arizona not observe Daylight Saving Time?

Arizona opted out of DST in 1968 to avoid an extra hour of summer evening sun in the desert heat. The Navajo Nation, which extends into Arizona, does observe DST to stay aligned with parts of the reservation in Utah and New Mexico. The Hopi Reservation, surrounded by the Navajo Nation, follows the rest of Arizona and does not observe DST.

When were US time zones first standardized?

Railroads created the first uniform 'standard time' system on November 18, 1883 — a day called 'The Day of Two Noons' because cities reset their clocks at noon to match the new zones. Congress made the system federal law with the Standard Time Act of 1918. The Uniform Time Act of 1966 standardized DST start and end dates nationwide.

Does Hawaii observe Daylight Saving Time?

No. Hawaii has not observed Daylight Saving Time since 1947. Because Hawaii is close to the equator, daylight length barely changes between summer and winter, so shifting the clock provides no real benefit. Most of Arizona also opts out for similar reasons of climate and geography.

May 2, 2026

How Many Time Zones Are in the USA?

The 50 United States span six time zones. If you count US territories, the answer is nine. From the easternmost point of Maine to the westernmost edge of American Samoa, the United States stretches across nearly half the planet — a fact that has shaped how Americans run railroads, schedule TV broadcasts, and decide what time to call grandma. Below: every zone, every UTC offset, the thirteen states split down the middle, and the two states that quietly refuse to spring forward.

Wall clock against a textured background — illustrating timekeeping across regions

Photo: Unsplash

The Direct Answer: 6 in the States, 9 With Territories

The 50 US states sit across six time zones: Eastern, Central, Mountain, Pacific, Alaska, and Hawaii-Aleutian. That is the answer most people are looking for when they ask "how many time zones are in the USA?"

But the United States as a federal entity is bigger than just the 50 states. Five inhabited US territories — Puerto Rico, the US Virgin Islands, American Samoa, Guam, and the Northern Mariana Islands — sit in three additional zones. So if you are answering a geography test, the precise answer is 9 time zones across all US lands.

For history and reasoning, see our companion explainer: Time Zones Explained: Why Does the US Have 6 of Them?

All Nine US Time Zones, Named

Here is the full list of US time zones, west to east, with their standard-time UTC offsets. Each shifts forward one hour during Daylight Saving Time, except where noted.

Zone	Abbrev.	Standard	Where
Samoa	SST	UTC-11	American Samoa
Hawaii-Aleutian	HAST	UTC-10	Hawaii, western Aleutian Is.
Alaska	AKST	UTC-9	Most of Alaska
Pacific	PST	UTC-8	CA, OR, WA, NV, parts of ID
Mountain	MST	UTC-7	CO, UT, WY, MT, AZ (no DST), NM, parts of ID/OR/KS/ND/SD/TX/NE
Central	CST	UTC-6	14 states fully + 8 split states
Eastern	EST	UTC-5	17 states fully + 5 split states
Atlantic	AST	UTC-4	Puerto Rico, US Virgin Islands
Chamorro	ChST	UTC+10	Guam, N. Mariana Islands

Wake Island, an unorganized US territory in the Pacific, technically uses UTC+12. It is uninhabited apart from a small military and contractor presence, so most lists skip it.

13 States Split Across Two Time Zones

Time zone boundaries do not always follow state lines. Thirteen states are split across two zones, usually because parts of the state had stronger trade or transportation ties to a neighbor in a different zone:

Alaska (Alaska + Hawaii-Aleutian — the far western Aleutians), Florida (Eastern + Central — the panhandle west of the Apalachicola River), Idaho (Mountain + Pacific), Indiana (Eastern + Central — see Indiana Fast Facts), Kansas (Central + Mountain), Kentucky (Eastern + Central), Michigan (Eastern + Central — most of the state is Eastern, with a few western Upper Peninsula counties on Central), Nebraska (Central + Mountain), North Dakota (Central + Mountain), Oregon (Pacific + Mountain — Malheur County), South Dakota (Central + Mountain), Tennessee (Eastern + Central — split roughly in the middle of the state), and Texas (Central + Mountain — El Paso and a sliver of west Texas).

Florida has the most dramatic split for travelers: drive west out of Tallahassee and at the Apalachicola River you cross from Eastern to Central Time and gain an hour. Tennessee's split runs roughly along the Cumberland Plateau — Knoxville is on Eastern, Nashville on Central.

Why the US Has Six (or Nine) Time Zones

The straightforward reason is geography: the contiguous United States spans roughly 58 degrees of longitude — 4 zones at 15 degrees each. Add Alaska's long reach across the north and Hawaii's position deep in the Pacific, and you get six zones for the 50 states.

Before 1883, every American city kept its own "local mean time" based on the position of the sun. A traveler going from Boston to Buffalo passed through dozens of slightly different times. Railroads found this unworkable: schedules made no sense if every station ran on a different clock. On November 18, 1883, US and Canadian railroads jointly imposed four standard zones — a day called "The Day of Two Noons" because cities reset their clocks at noon.

Congress made the zones federal law with the Standard Time Act of 1918. Daylight Saving Time was added on and off until the Uniform Time Act of 1966 standardized DST nationwide. Alaska's many small zones were consolidated into the modern Alaska zone in 1983.

The DST Exceptions: Arizona and Hawaii

Hawaii has not observed Daylight Saving Time since 1947. Daylight length barely changes near the equator, so shifting the clock provides no real benefit. See Hawaii Fast Facts for more on the geography.

Most of Arizona opted out of DST in 1968. The state argued that an extra hour of summer evening sun in 110-degree desert heat made cooling more expensive and outdoor evening activity less pleasant. The exception: the Navajo Nation, which extends across Arizona, Utah, and New Mexico, observes DST to keep all of its land on the same clock. The Hopi Reservation, which is surrounded by the Navajo Nation, follows the rest of Arizona and does not. The result: in summer, you can drive across northeast Arizona and pass through the same time zone three times.

Indiana is the most recent state to harmonize. Until 2006, different counties followed Eastern, Central, and DST-or-no-DST in a confusing patchwork. The state legislature finally adopted statewide DST in 2006 — though the Eastern/Central county split itself remains.

Time Zones in the US Territories

The three territory time zones are easy to forget, but they are real US zones with real Americans living in them.

Atlantic Standard Time (UTC-4) — Puerto Rico and the US Virgin Islands. Atlantic time is one hour ahead of Eastern. Neither territory observes DST, so for half the year they are on the same clock as the East Coast, and for the other half they are an hour ahead.

Samoa Standard Time (UTC-11) — American Samoa. This is the latest time zone in any US jurisdiction. When it is noon Monday in New York, it is 6:00 AM Monday in American Samoa.

Chamorro Standard Time (UTC+10) — Guam and the Northern Mariana Islands. This is the only US time zone ahead of UTC. When it is noon Monday in New York, it is 2:00 AM Tuesday in Guam — meaning Americans in Guam often see the next calendar day before anyone in the 50 states.

Test Your US Geography

The geography of US time zones rewards anyone who knows which states sit where. Try the daily GeoProwl game — every clue ties back to data from the Census Bureau, NOAA climate records, or USDA agriculture, and the locations are spread across all six time zones. Or jump straight into Just States to see if you can pin every state on the map without a hint.

For more US geography deep dives, read about the Four Corners quadripoint, the 27 landlocked states, and every state's highest and lowest elevation.