Americas · North America · Sovereign state
Current time in United States
Spans 8 time zones from UTC-10:00 to UTC-04:00, a 6-hour difference. 27 of 29 zones currently in DST.
Saturday, May 30, 2026
About United States's time
8 time zones.
The United States spans an incredible 29 time zones when you count all its territories, stretching from UTC-10 in Hawaii to UTC+10 in Guam. Most of the mainland operates across just four zones, but the patchwork of DST observance—plus holdouts like Arizona—makes it a surprisingly complex timekeeping landscape.
Next clock change
2026 Sunday · clocks fall back
Clocks fall back by one hour · in 5 months.
Affects 27 of 29 zones.
Daylight saving schedule
By time zone
Time zones of United States.
8 time zones
Major cities
Cities of United States.
Territories & dependencies
The Republic, around the world.
History
How United States keeps time.
Before 1883, every American city kept its own local solar time, creating chaos for the rapidly expanding railroad industry. On November 18, 1883, the major railroads implemented a system of four continental time zones—Eastern, Central, Mountain, and Pacific—known as 'The Day of Two Noons.' This system was later formalized internationally at the 1884 International Meridian Conference.
The Standard Time Act of 1918 officially established time zones in U.S. law and also introduced Daylight Saving Time, though DST was repealed after World War I and left to local option. During World War II, year-round DST was mandated again (1942–1945) as 'War Time.' The patchwork of local DST observance that followed led to widespread confusion—a 1960s incident saw a bus route crossing seven time zones between West Virginia and Ohio alone.
The Uniform Time Act of 1966 standardized DST across the country, requiring states that observed it to follow consistent start and end dates. States were given the option to opt out entirely, which Arizona (except the Navajo Nation) and Hawaii chose to do. The Energy Policy Act of 2005 extended DST by about four weeks, starting in 2007, moving the start to the second Sunday in March and the end to the first Sunday in November.
In 2022, the U.S. Senate passed the Sunshine Protection Act to make DST permanent nationwide, but the bill stalled in the House. As of now, the biannual clock change remains the norm in most states, though the debate continues.
Did you know?
Things about United States's time.
The U.S. has one of the most complicated timekeeping systems in the world, largely because of its territories. While the contiguous 48 states use just four time zones, the full picture includes 29 zones when you count Alaska, Hawaii, and overseas territories like Guam (UTC+10), American Samoa (UTC-11), Puerto Rico (UTC-4), and the U.S. Virgin Islands (UTC-4). This means it can be Tuesday in American Samoa and already Wednesday in Guam simultaneously.
Arizona is the most famous DST exception—it stays on Mountain Standard Time year-round, meaning that for part of the year it aligns with Pacific Time and for the rest it matches Mountain Daylight Time. But the plot thickens: the Navajo Nation, which extends into Arizona, Utah, and New Mexico, does observe DST, while the Hopi Reservation, entirely surrounded by the Navajo Nation, does not. Driving through this region can mean changing clocks multiple times in a single trip.
Indiana was notoriously late to the DST game. Until 2006, large portions of the state did not observe Daylight Saving Time, and some counties switched zones between Eastern and Central based on which major city they had stronger economic ties to. The entire state finally adopted DST in 2006, though a few counties near Chicago and Louisville still straddle the Eastern/Central divide.
Several U.S. time zones also slice through individual states in unusual ways. Florida's panhandle is in Central Time while the rest of the state is Eastern. Michigan's Upper Peninsula is split, with four counties on Central Time. Oregon and Idaho share a time zone boundary that runs along the Snake River in some places, meaning two neighboring towns in different states can be in the same zone—or different ones—depending on the exact location.
Frequently asked questions
Common questions about United States's time zone, daylight saving rules, and how to handle it in software. Can't find what you need? Email [email protected].
- How many time zones are there in the United States?
- The U.S. proper uses 9 named time zones (Atlantic, Eastern, Central, Mountain, Alaska, Hawaii-Aleutian, Samoa, Chamorro, and Pacific), but when you count all the individual zone entries used across states, territories, and historical variations, the total reaches 29. The contiguous 48 states use just four: Eastern, Central, Mountain, and Pacific.
- Does every U.S. state observe Daylight Saving Time?
- No. Arizona (except the Navajo Nation) and Hawaii do not observe DST. All other states and territories follow it, though there is ongoing legislative debate about making DST permanent or abolishing it entirely.
- Why doesn't Arizona observe Daylight Saving Time?
- Arizona opted out of DST in 1968, largely because of the state's extreme summer heat. The logic was that shifting an extra hour of daylight into the evening would mean people using more energy to cool their homes during the hottest part of the day. The Navajo Nation within Arizona does observe DST, creating a unique situation where time changes depending on which part of the state you're in.
- What time zone is Puerto Rico in?
- Puerto Rico and the U.S. Virgin Islands use Atlantic Standard Time (UTC-4) year-round. They do not observe Daylight Saving Time, so they align with Eastern Daylight Time during summer months but fall back to being one hour ahead of Eastern Standard Time in winter.
- Can I travel between time zones without leaving the U.S.?
- Absolutely. Driving from Maine to California takes you through four time zones. Even within a single state, you can cross zone boundaries—driving across Indiana, Florida, or Michigan can mean changing your clock without crossing a state line.
- When do clocks change for Daylight Saving Time?
- Since 2007, clocks spring forward on the second Sunday in March and fall back on the first Sunday in November. This gives the U.S. about 8 months of DST and about 4 months of standard time each year.
- What time zone is Guam in?
- Guam uses Chamorro Standard Time (UTC+10), which does not observe DST. It's one of the first places on Earth to see a new day—when it's noon on Monday in New York, it's already 2:00 AM on Tuesday in Guam.
- Is the U.S. going to stop changing clocks?
- Possibly, but not yet. The Sunshine Protection Act, which would make DST permanent nationwide, passed the Senate in 2022 but did not advance in the House of Representatives. Until new legislation passes, the biannual clock changes will continue in most states.
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