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Time Zones in the United States

Multiple Time Zones

Country: United States
Long Name: United States of America
Abbreviations: US, USA
Capital: Washington DC
Time Zones: 7 (Main Country)
Total Time Zones: 13 (with dependencies)
Dial Code: +1

Time Zones Currently Being Used in United States

OffsetTime Zone Abbreviation & NameExample CityCurrent Time
UTC -10HSTHawaii Standard TimeHonoluluThu, 8:35:21 am
UTC -9HDTHawaii-Aleutian Daylight TimeAdakThu, 9:35:21 am
UTC -8AKDTAlaska Daylight TimeAnchorageThu, 10:35:21 am
UTC -7PDTPacific Daylight TimeLos AngelesThu, 11:35:21 am
MSTMountain Standard TimePhoenixThu, 11:35:21 am
UTC -6MDTMountain Daylight TimeSalt Lake CityThu, 12:35:21 pm
UTC -5CDTCentral Daylight TimeChicagoThu, 1:35:21 pm
UTC -4EDTEastern Daylight TimeNew YorkThu, 2:35:21 pm

How Many Time Zones Are There in the US?

There are 9 time zones by law in the USA and its dependencies. However, adding the time zones of 2 uninhabited US territories, Howland Island and Baker Island, brings the total count to 11 time zones.

The contiguous US has 4 standard time zones. In addition, Alaska, Hawaii, and 5 US dependencies all have their own time zones. As neither Hawaii nor the 5 dependencies use Daylight Saving Time (DST), there are only 6 corresponding DST time zones.

A 12th Time Zone?

Since Howland Island and Baker Island constitute the world's westernmost landmasses in relation to the International Date Line, making them the last places on Earth where any date exists, they are sometimes assigned a theoretical 12th time zone called Anywhere on Earth (AoE).

Generalized Time Zones in United States

Time Zone Abbreviation & NameOffsetCurrent Time
PTPacific TimeUTC -8:00 / -7:00Thu, 11:35:21 am
MTMountain TimeUTC -7:00 / -6:00Thu, 12:35:21 pm
CTCentral TimeUTC -6:00 / -5:00Thu, 1:35:21 pm
ETEastern TimeUTC -5:00 / -4:00Thu, 2:35:21 pm

The time zones in the contiguous US are often referred to by their generic name, without making a difference between standard time and Daylight Saving Time designations. For example, Eastern Time (ET) refers to Eastern Standard Time (EST) or Eastern Daylight Time (EDT), depending on which is currently in use. In practice, this means that the local time in these time zones changes when DST begins and ends.

Note: Local time in these time zones changes when Daylight Saving Time begins and ends.

Time Zones Not Currently Being Observed in United States

OffsetTime Zone Abbreviation & NameCommences
UTC -9AKSTAlaska Standard TimeNov 3, 2024
UTC -8PSTPacific Standard TimeNov 3, 2024
UTC -6CSTCentral Standard TimeNov 3, 2024
UTC -5ESTEastern Standard TimeNov 3, 2024

The above time zones are used during other parts of the year. They will become active again after the next clock change as Daylight Saving Time begins or ends.

Time Zones Being Used in Dependencies of United States

OffsetTime Zone Abbreviation & NameDependencyTypeCurrent Time
UTC -12AoEAnywhere on EarthUS Minor Outlying IslandsTerritoryThu, 6:35:21 am
UTC -11SSTSamoa Standard TimeAmerican SamoaUnincorp. unorg. territoryThu, 7:35:21 am
SSTSamoa Standard TimeUS Minor Outlying IslandsTerritoryThu, 7:35:21 am
UTC -10HSTHawaii Standard TimeUS Minor Outlying IslandsTerritoryThu, 8:35:21 am
UTC -4ASTAtlantic Standard TimePuerto RicoUnincorp. org. territoryThu, 2:35:21 pm
ASTAtlantic Standard TimeUS Virgin IslandsUnincorp. org. territoryThu, 2:35:21 pm
UTC +10ChSTChamorro Standard TimeGuamUnincorp. org. territoryFri, 4:35:21 am
ChSTChamorro Standard TimeNorthern Mariana IslandsUnincorp. org. territoryFri, 4:35:21 am
UTC +12WAKTWake TimeUS Minor Outlying IslandsTerritoryFri, 6:35:21 am

The US dependencies don't use DST.

The United States' Time Zone History

The US was divided into 4 standard time zones on November 18, 1883, and jurisdiction for the zones was given to the Interstate Commerce Commission (ICC). Since 1967, the US Department of Transportation (DOT) has been responsible for governing time zones in the country.

Time zones in the USA are defined in the U.S. Code, Title 15, Chapter 6, Subchapter IX - Standard Time. The time zones in the law are defined by their offset from Coordinated Universal Time (UTC).

There are 9 official time zones according to the law. In addition the uninhabited atolls of Baker Island (AoE) and Wake Island (WAKT) add to the time zone count, making 11 the total number of time zones in the US.

Almost all states in the US use Daylight Saving Time (DST). Most of Arizona and Hawaii don't use DST. Indiana introduced DST in 2006.

Thursday, July 18, 2024