September 17, 2026 8 min read

US Time Zones: Map, States and the States Split Between Two Zones

The United States has nine standard time zones in federal law: Atlantic, Eastern, Central, Mountain, Pacific, Alaska, Hawaii-Aleutian, Samoa and Chamorro. The 50 states use six of them, from Eastern (UTC-5) to Hawaii-Aleutian (UTC-10). Fourteen states are split between two zones, and Arizona and Hawaii stay on standard time all year.

How many time zones the US has

Federal law divides US territory into nine zones (15 U.S.C. 261) and names them in order from east to west (15 U.S.C. 263). Each zone is a fixed number of hours from Coordinated Universal Time, from UTC-4 for Atlantic to UTC-11 for Samoa, with Chamorro on the other side of the date line at UTC+10.

Only six of the nine touch the 50 states. The contiguous US uses four: Eastern, Central, Mountain and Pacific. Alaska adds the Alaska zone, and Hawaii plus the far western Aleutian Islands share Hawaii-Aleutian. Atlantic covers Puerto Rico and the US Virgin Islands, Samoa covers American Samoa, and Chamorro covers Guam and the Northern Mariana Islands. If you want the general idea behind offsets first, start with how time zones work.

The zones and their offsets

Offsets below were checked against the tz database (tzdata 2026d, the zone files most phones and computers use). Summer offsets apply from the second Sunday in March to the first Sunday in November; the next change is 1 November 2026, when clocks go back an hour.

When it is noon EST in New York in January, it is 11 AM in Chicago, 10 AM in Denver and Phoenix, 9 AM in Los Angeles, 8 AM in Anchorage, 7 AM in Honolulu and 6 AM in Pago Pago. In Guam it is already 3 AM the next day. In July, Phoenix and Honolulu drop one more hour behind New York because they do not move their clocks. The abbreviation pages explain each label in full: EST, CST, MST and PST. For the gap people ask about most, see the difference between EST and PST.

States split between two zones

Zone lines follow county lines, rivers and even section lines, not state borders, so 14 states have parts in two zones. This list follows the boundary descriptions in 49 CFR Part 71.

Indiana is the state that confuses people most, and with reason. From 1971 through 2005 most of it stayed on Eastern Standard Time all year, and the whole state began observing daylight saving time only in April 2006. Counties then moved back and forth across the line for a few years; the tz database still keeps separate zones such as America/Indiana/Knox (Starke County) and America/Indiana/Tell_City (Perry County) to record that history. Today Indianapolis is Eastern.

Texas is the other common question. Nearly all of it, including Houston, Dallas and San Antonio, is Central. Only the far west is Mountain, which is why El Paso is an hour behind the rest of the state. Michigan works the opposite way from what many expect: Detroit and most of the state are Eastern, and only the four western Upper Peninsula counties use Central.

Who skips daylight saving time

Federal law lets a state stay on standard time all year, either statewide or for the part of the state in one zone (15 U.S.C. 260a). Two states use that option today.

• Arizona. State law fixes Arizona on "standard mountain time" and "elects to reject" daylight saving time (A.R.S. 1-242). Phoenix is on MST, UTC-7, all year, so it matches Denver in winter and Los Angeles in summer.
• The Navajo Nation is the exception inside Arizona. It spans Arizona, New Mexico and Utah and observes daylight saving time across its whole territory, following Denver's clock. The Hopi Reservation, which sits inside the Navajo Nation, follows the rest of Arizona.
• Hawaii. It stays on HST, UTC-10, all year. Alaska's Aleutian Islands share the zone but do observe daylight saving time, so in summer Adak is an hour ahead of Honolulu.
• The territories. Puerto Rico, the US Virgin Islands, Guam, the Northern Mariana Islands and American Samoa do not change their clocks.

The full list, with the history of states that tried other arrangements, is in states that do not observe daylight saving time. If the summer and winter labels themselves are the problem, EST vs EDT explains which one applies when.

Who sets zone boundaries

The US Department of Transportation does. Under 15 U.S.C. 261, the limits of each zone are set by order of the Secretary of Transportation, "having regard for the convenience of commerce", and the current lines are published as 49 CFR Part 71. The zones began as railroad time, and the regulation still lists the rail junctions where certain carriers may change their clocks.

Moving a boundary is a federal rulemaking, not a state vote. A county or state asks DOT, DOT takes public comments and decides whether the move serves local commerce, and the result is amended into Part 71. That is how the Indiana counties changed sides in 2006 and 2007. Daylight saving time is separate: a state can opt out of it on its own, but it cannot adopt permanent summer time without Congress.

Time in major US cities

Each city page shows the current local time, the offset in effect today and the date of the next clock change:

• Eastern: New York, also the reference for most of the East Coast.
• Central: Chicago, with Houston, Dallas, Nashville and Minneapolis on the same clock.
• Mountain: Denver observes daylight saving time; Phoenix does not.
• Pacific: Los Angeles, with Seattle, San Francisco and Las Vegas.
• Alaska and Hawaii: the America/Anchorage and Pacific/Honolulu zone pages.

For every city and zone in one place, use the United States time page. To check a call across two of these zones on a specific date, put both cities into the time zone converter.

Frequently asked questions