How Many Time Zones in The Usa

How Many Time Zones in The Usa (United States)


By law, time in the United States (US) and its possessions is divided into nine standard time zones. However, the 50 states are spread across six standard time zones: Pacific, Central, Mountain, Eastern, Alaska, and Hawaii. The other three time zones are used in US territories: the Atlantic Time Zone is followed in Puerto Rico and the US Virgin Islands; the Chamorro Time Zone is followed in Guam; and the Samoa Time Zone is followed in American Samoa. Most states observe Daylight Saving Time (DST), which begins at 0200 hours on the second Sunday of March and runs until 0159 hours on the first Sunday of November. DST is not observed in the states of Hawaii and Arizona, and some US territories including Puerto Rico, Guam, American Samoa, and the Virgin Islands. most common question is that how many time zones in the usa

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.

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).

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.

Read Also-Ministry of Urban Development Launched Smart Cities Mission Portal

Before the invention of clocks, the time of day was determined by apparent solar time. For example, a sundial was used to estimate the time based on the Sun’s apparent position in the sky. When mechanical clocks became common in the 19th century, mean solar time was used. Apparent and mean solar time may differ by up to 15 minutes. Further advances led to the concept of standard time zones. Time zones are regions on the globe that observe the same standard time. The local time in a given time zone is defined by its offset from Coordinated Universal Time (UTC), which is the primary time standard used throughout the world. UTC time either changes backward or forward by one hour for every 15 degrees west or east of the prime meridian.

The 50 United States Of America


Hawaii-Aleutian Time Zone

The Hawaii-Aleutian Time Zone derives its name from two areas: Hawaii and the Aleutian Islands in Alaska. These two areas do not use daylight saving time. The time zone observes Hawaii-Aleutian Standard Time (HAST), which is obtained by subtracting 10 hours from UTC (UTC-10:00). Some of the major metropolitan areas under this time zone include Honolulu, Hilo, and Kapaa.

Alaska Time Zone
The Alaska Time Zone encompasses almost the entire state of Alaska. Standard time is observed in this time zone by subtracting 9 hours from UTC (UTC-09:00) and 8 hours during DST (UTC-08:00). The clock time in the Alaska Time Zone is based on the mean solar time at 135 degrees west of Greenwich Observatory.

Pacific Time Zone-
The Pacific Time Zone (PT) encompasses the western states of the US, western Mexico, and western Canada. The standard time within this zone is observed by subtracting 8 hours from UTC (UTC-8). During DST, an offsite time of UTC-7 is used. PST is one hour ahead of Hawaii and Alaska Time Zones, and at least one hour behind the other time zones.

Mountain Time Zone-
The Mountain Time Zone (MT) observes standard time by subtracting 7 hours from UTC (UTC-07:00) and 6 hours during DST (UTC-06:00). In the US, this time zone is generally known as Mountain Time (MT). Five states, namely Colorado, New Mexico, Wyoming, Utah, and Montana, are included within the Mountain Time zone.

Central Time Zone-
The Central Time Zone (CT) encompasses nine states in the US, the Canadian province of Manitoba, and most of Mexico. It is observed by subtracting six hours from UTC (UTC-06:00). Most of the zone uses DST during summer and changes to Central Daylight Time (CDT), which is 5 hours behind UTC.

Eastern Time Zone

The Eastern Time Zone (ET) encompasses most of the 22 states in the eastern United States. Places within this time zone are 5 hours behind UTC. The northern part of ET is advanced by one hour to 0300 hours EDT at 0200 hours EST on the first Sunday of March. On the first Sunday of November, the time is moved back by one hour at 0200 hours EDT to 0100 hours EST.

Read Also-Where Is Idar Located In India

Leave a Comment