United States Time Zone Map

Standard Time Zones of the USA

USA Time Zones

NOTE: Indiana observes Daylight Savings Time starting 2006

United States time zones are nine standard time zones covering the states and possessions of the United States, used in conjunction with state and national legislation regarding the use of Daylight Saving Time.

Daylight Saving Time (also called DST, or summer time) is the portion of the year in which a region's local time is advanced by (usually) one hour from its official standard time. It is most common in temperate regions.

"Daylight saving time" is a system intended to "save" daylight, as opposed to "wasting" time. The official time is adjusted forward during the spring and summer months, so that the active hours of work and school will better match the hours of daylight.

Zones used in the contiguous USA

From east to west, these zones are:

Eastern Standard Time (EST; GMT−5; Zone R), which comprises roughly the states on the Atlantic coast plus some other areas away from both the Gulf of Mexico and the Mississippi River.

Central Standard Time (CST; GMT−6; Zone S), which comprises roughly the states on the Mississippi River plus nearly a full state further west.

Mountain Standard Time (MST; GMT−7; Zone T), which comprises roughly the states that include the Continental Divide and Rocky Mountains plus much of the Great Basin and the watershed of the Colorado River.

Pacific Standard Time (PST; GMT−8; Zone U), which comprises roughly the states on the Pacific coast, plus Nevada.

Zones used in states beyond the contiguous USA

Alaska Standard Time (AKST; GMT−9; Zone V), which comprises most of the state of Alaska.

Hawaii-Aleutian Standard Time (or unofficially Hawaii Standard Time) (HST; GMT−10; zone W), which includes Hawaii and most of the length of the Aleutian Islands chain (west of 169°30'W).

Zones outside the United States:

Atlantic Standard Time (AST, GMT−4, Zone Q), which comprises Puerto Rico and the U.S. Virgin Islands.

Samoa Standard Time (GMT−11, Zone X), which comprises American Samoa.

Chamorro Standard Time (GMT+10, Zone K), which comprises Guam and the Northern Mariana Islands.