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Metronome, a public art installation showing the time in New York City

The Eastern Time Zone (ET) of the Western Hemisphere  – also known as North American Eastern Standard Time (NAEST)  – is a time zone that falls mostly along the east coast of North America and the west coast of South America. Its UTC time offset is −5 hrs (UTC-05) during standard time and -4 hrs (UTC-04) during daylight saving time. The clock time in this zone is based on the mean solar time of the 75th meridian west of the Greenwich Observatory.

In the United States and Canada, this time zone is generally called Eastern Time (ET). Specifically, it is Eastern Standard Time (EST) when observing standard time (winter), and Eastern Daylight Time (EDT) when observing daylight saving time (summer).

The 1966 Uniform Time Act in the USA meant that EDT was instituted on the last Sunday in April, starting in 1966, throughout most of the USA.^[1] EST would be re-instituted on the last Sunday in October. The act was amended to make the first Sunday in April the beginning of EDT as of 1987.^[1] The Energy Policy Act of 2005 extended daylight saving time in the U.S. beginning in 2007. The local time changes at 02:00 EST to 03:00 EDT on the second Sunday in March and returns at 02:00 EDT to 01:00 EST on the first Sunday in November^[1]. In Canada, the time changes as it does in the U.S.^[2]

Use

North America

North American Eastern Time Zone (shown in the furthest right yellow)

Canada

In Canada, the following provinces and territories are part of the Eastern Time Zone:

• Ontario (excluding areas west of Thunder Bay but including Atikokan)
• Quebec (excluding far eastern Côte-Nord and the Magdalen Islands)
• East-central Nunavut (including part of Melville Peninsula and most of Ellesmere and Baffin Islands, including Iqaluit; Southampton Island does not observe DST)

United States

In the United States, 17 states and the District of Columbia are entirely located within the Eastern Time zone, while another six are split between the Eastern and Central time zones.

These states and Washington, D.C. observe only Eastern Time:

The exact specification for the location of time zones and the dividing line between zones is set forth in the Code of Federal Regulations at 49 CFR 71.^[3]

These six states are split between Eastern and Central time:

• Alabama: The entire state is officially in the Central Time Zone. However, a handful of communities unofficially observe Eastern Time because they are part of the Columbus, Georgia metropolitan area - Phenix City, Smiths Station, Lanett, and Valley.^[4]
• Florida: All of Florida is in the Eastern Time zone except for the portion of the Florida panhandle west of the Apalachicola River. As the Eastern-Central zone boundary approaches the Gulf of Mexico, it follows the Bay/Gulf county line. There is some discrepancy whether or not the Dry Tortugas are in the Eastern or Central Time Zone. Some sources claim the Eastern Time Zone, while others claim Central Time Zone. Either way the Dry Tortugas lie near the boundary of the two time zones.
• Indiana: All of Indiana observes Eastern Time except for six northwestern counties in the Chicago metropolitan area and six southern counties in the Evansville metropolitan area.
  • Until 2006, the portions of Indiana within the Eastern Time Zone observed Eastern Standard Time year-round—except that five counties near Cincinnati and Louisville customarily observed Eastern Daylight Time despite legally being on Eastern Standard Time. See Time in Indiana.
• Kentucky: Roughly, the eastern half of the state, including all of metropolitan Louisville is in the Eastern Time Zone and the western half is in the Central Time Zone; however, the boundary is not a neat "north-south" line but runs northwest-southeast.
• Michigan: All of Michigan observes Eastern Time except the four westernmost counties, in the Upper Peninsula along the border with Wisconsin, which observe Central Time - Gogebic, Iron, Dickinson, Menominee. Historically the entire state observed Central Time. When Daylight Saving Time was first introduced, the Lower Peninsula remained on DST after it formally ended, effectively re-aligning itself into the Eastern Time Zone. The Upper Peninsula continued to observe Central Time until 1972, when all but the four counties noted changed to Eastern Time.
• Tennessee: The eastern third of Tennessee is in the Eastern Time Zone. The area is roughly but not entirely coextensive with the region formally known as "East Tennessee".

Eastern Time is also used somewhat as a de facto official time for all of the United States, since it includes the capital (Washington, D.C.), the largest city (New York City), and approximately half the country's population. National media organizations will often report when events happened or are scheduled to happen in Eastern Time even if they occurred in another time zone, and TV schedules are also almost always posted in Eastern Time. Major professional sports leagues also post all game times in Eastern time, even if both teams are from the same time zone, outside of Eastern Time. For example a game time between two teams from Pacific Time Zone will still be posted in Eastern time (for example, one may see "Seattle at Los Angeles" with "10:00 pm" posted as the start time for the game, often without even clarifying the time is posted in Eastern time).

Most cable channels advertise airing times in Eastern time, sometimes including either Central or Pacific time, depending on whether there is a separate western feed. If there is a separate western feed, it generally airs the same programming delayed by three hours, in which case a program may be advertised as 8PM "Eastern and Pacific." Those in the Mountain time zone will see the program at 9PM (assuming they receive the west feed) and those in Central time zone will see it at 7PM (assuming they receive the east feed).^{[citation needed]}

Mexico

• Quintana Roo: this eastern state followed EST for an almost-17-year period (1982 to some time in 1998). [See http://www.diputados.gob.mx/bibliot/publica/inveyana/polisoc/horver/capitulo5.htm ](Spanish)

Central America

The countries that use Eastern Time Zone include:

• Panama

Caribbean

The following western Caribbean nations and territories in the Eastern Time Zone are:

• Jamaica
• Haiti
• Cayman Islands
• Cuba
• the Bahamas

The eastern Caribbean islands are in the Atlantic Time Zone (UTC-4), sometimes called Eastern Caribbean Time Zone. This time zone includes the U.S. Virgin Islands and Puerto Rico. Atlantic/Eastern Caribbean Time is one hour ahead of Eastern Time.

The Eastern/Atlantic time zone boundary divides the island of Hispaniola, with Haiti on Eastern Time and the Dominican Republic on Atlantic Time.

Because they are located in the tropics, many Caribbean islands do not observe Daylight Saving Time. Thus, when the mainland United States is on D.S.T., those islands in the Atlantic Time zone are on the same time as Eastern Daylight Time, while those in the Eastern Time zone are on the same time as Central Daylight Time.

South America

In South America this time zone is observed in:

• Colombia
• Ecuador (except Galápagos)
• Peru

Australia

The term 'EST' also describes domestic usage of the Australian Eastern Standard Time/AEST (UTC +10:00) timezone.

Major metropolitan areas

See also List of places in the UTC-5 timezone

See also

• Time in Indiana
• Time in the United States
• Time in Canada
• Time in Brazil
• Time in Mexico
• Time in Australia

Sources

• Official U.S. time in the Eastern time zone
• World time zone map
• U.S. time zone map
• History of U.S. time zones and UTC conversion
• Canada time zone map
• Time zones for major world cities
• Official times across Canada
• Federal Regulations defining time zones

References