How Many Time Zones in the USA?
The United States spans an impressive nine official time zones, encompassing not only the 50 states but also its inhabited territories. While most people are familiar with the six main zones that cover the contiguous states and Alaska/Hawaii (Eastern, Central, Mountain, Pacific, Alaska, and Hawaii-Aleutian), three additional zones apply to US territories: Atlantic Time (Puerto Rico and US Virgin Islands), Samoa Time (American Samoa), and Chamorro Time (Guam and Northern Mariana Islands). This article breaks down all nine, providing offsets from UTC and listing the areas each covers. For live clock references, visit Time.now.
| Time Zone Name | UTC Offset (Standard Time) | Areas Covered |
|---|---|---|
| Eastern Time (ET) | UTC-5 | East Coast states, e.g., New York, Florida, Washington DC |
| Central Time (CT) | UTC-6 | Midwest and South, e.g., Illinois, Texas, Louisiana |
| Mountain Time (MT) | UTC-7 | Rocky Mountain states, e.g., Colorado, Arizona (no DST), Utah |
| Pacific Time (PT) | UTC-8 | West Coast states, e.g., California, Oregon, Washington |
| Alaska Time (AKT) | UTC-9 | Most of Alaska (except western Aleutians) |
| Hawaii-Aleutian Time (HST) | UTC-10 | Hawaii and western Aleutian Islands (Alaska) |
| Atlantic Time (AST) | UTC-4 | Puerto Rico, US Virgin Islands |
| Samoa Time (SST) | UTC-11 | American Samoa |
| Chamorro Time (ChST) | UTC+10 | Guam, Northern Mariana Islands |
The Six Main US Time Zones
The contiguous United States is divided into four standard time zones: Eastern, Central, Mountain, and Pacific. Alaska and Hawaii add two more, making six that cover the states. The boundaries are defined by law and have evolved over time. For detailed maps and boundary descriptions, see the US Time Zone Map. Each of these zones observes Daylight Saving Time (DST) except for Hawaii and most of Arizona. For more on Arizona's unique status, read Does Arizona Use DST?.
Eastern Time (ET)
Eastern Time (UTC-5 standard, UTC-4 DST) covers roughly the eastern third of the country, including major cities like New York, Washington DC, and Atlanta. It is the most populous time zone in the US. For more details, visit Eastern Time (ET).
Central Time (CT)
Central Time (UTC-6 standard, UTC-5 DST) spans from the Great Lakes down to the Gulf Coast, including Chicago, Dallas, and New Orleans. Learn more at Central Time (CT).
Mountain Time (MT)
Mountain Time (UTC-7 standard, UTC-6 DST) covers the Rocky Mountain region, including Denver and Salt Lake City. However, Arizona does not observe DST, remaining on Mountain Standard Time year-round. See Mountain Time (MT) for details.
Pacific Time (PT)
Pacific Time (UTC-8 standard, UTC-7 DST) covers the West Coast, including Los Angeles, San Francisco, and Seattle.
Alaska Time (AKT)
Alaska Time (UTC-9 standard, UTC-8 DST) covers most of Alaska, except the western Aleutian Islands which use Hawaii-Aleutian Time.
Hawaii-Aleutian Time (HST)
Hawaii-Aleutian Time (UTC-10 standard, no DST in Hawaii) covers Hawaii and the western Aleutian Islands. Hawaii does not observe DST.
Territory Time Zones: Atlantic, Samoa, and Chamorro
In addition to the six state zones, three time zones cover US territories. These are often overlooked but are essential for official US timekeeping.
Atlantic Time (AST)
Atlantic Standard Time (UTC-4) is used in Puerto Rico and the US Virgin Islands. These territories do not observe DST, so their offset remains constant year-round. For example, when New York is on Eastern Daylight Time (UTC-4), Puerto Rico shares the same local time; but during Eastern Standard Time (UTC-5), Puerto Rico is one hour ahead.
Samoa Time (SST)
Samoa Time (UTC-11) is observed in American Samoa, a group of islands in the South Pacific. This is one of the latest time zones in the world (just west of the International Date Line). American Samoa does not observe DST.
Chamorro Time (ChST)
Chamorro Time (UTC+10) is used in Guam and the Northern Mariana Islands, located in the western Pacific. These islands are among the first US territories to see a new day. They also do not observe DST.
Daylight Saving Time in the US
Most of the United States observes Daylight Saving Time, which begins on the second Sunday in March and ends on the first Sunday in November. However, Hawaii and most of Arizona (except the Navajo Nation) do not observe DST. The US territories (Puerto Rico, US Virgin Islands, American Samoa, Guam, Northern Mariana Islands) also do not observe DST. For the 2026 schedule and details, see Daylight Saving Time USA 2026.
Why So Many Time Zones?
The United States spans a vast geographic area, from the Atlantic to the Pacific and into the Pacific Ocean. The use of multiple time zones ensures that solar time roughly matches local clock time. The six main zones were established by the Standard Time Act of 1918, while the territory zones were added as those territories came under US jurisdiction. For a visual guide, the US Time Zone Map shows all boundaries clearly.
Frequently Asked Questions
Q: How many time zones are there in the USA including territories?
A: There are 9 official time zones: Eastern, Central, Mountain, Pacific, Alaska, Hawaii-Aleutian, Atlantic, Samoa, and Chamorro.
Q: Does the US observe Daylight Saving Time in all time zones?
A: No. Hawaii and most of Arizona do not observe DST. All US territories (Puerto Rico, US Virgin Islands, American Samoa, Guam, Northern Mariana Islands) also do not observe DST.
Q: What is the time difference between the East Coast and Hawaii?
A: Eastern Time is 5 hours ahead of Hawaii-Aleutian Time during standard time (e.g., 12:00 PM ET = 7:00 AM HST). During DST, the difference is 6 hours.
Q: Which US time zone is furthest ahead?
A: Chamorro Time (UTC+10) is the furthest ahead. When it is 12:00 PM Monday in Guam, it is 10:00 PM Sunday in New York (Eastern Standard Time).
Q: Are there any US territories that use a different time zone than the ones listed?
A: No. All inhabited US territories use one of the three territory zones (Atlantic, Samoa, or Chamorro). Some uninhabited islands (e.g., Baker Island, Howland Island) use UTC-12, but these are not official time zones with permanent populations.
Q: Where can I see the current time in multiple US cities?
A: For a multi-city world clock view, visit CurrentTime.now. For worldwide non-US city times, try TimeRight.Now. For specific US cities, such as time in Miami, you can find dedicated pages.