Eastern Time Zone

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. 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).

Since 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, in the U.S. as well as in Canada.



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, so that 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][3]


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

United States

In the United States, 18 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.[4]

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.[5]
  • 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 and national broadcast networks advertise airing times in Eastern time. National broadcast networks (ABC, CBS, The CW, Fox Network, NBC) generally have two feeds, an eastern feed for Eastern and Central time zones, and a western feed for Mountain and Pacific time zones. The prime times, set on Eastern and Pacific, affect the adjoining time zones in opposite directions: Central time zone stations (receiving the eastern feed) start prime time at 7:00 PM, while Mountain time zone stations (receiving the western feed) start prime time 9:00 PM. Cable channels with a separate western feed (such as HBO, whose western feed is called "HBOW") generally air the same programming as the eastern feed delayed by three hours. Other cable networks such as the Discovery family of networks repeat their prime time programming three hours later; this allows for the same show to be advertised as airing at "8:00 PM E/P" (that is, "8:00 PM Eastern and Pacific time"). Networks specializing in the airing of sports events, such as ESPN, advertise all of their programming in Eastern and Pacific, incorporating the 3-hour time difference (as in "8:00 PM Eastern/5:00 PM Pacific") and leaving viewers in the remaining time zones to calculate start time in their own areas.


  • Quintana Roo: this eastern state followed EST for an almost-17-year period (1982 to some time in 1998).[6]

Central American and the Caribbean

Panama and several countries in the Caribbean use UTC−05 all year round.

Other places

For South American countries see UTC−05.

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


  1. a b c Prerau, David (2006). . . Web Exhibit. http://webexhibits.org/daylightsaving/e.html. Retrieved 2007-04-23. 
  2. Law, Gwillim (2007-09-21). . http://www.statoids.com/tus.html. 
  3. . Government of Ontario. 2008-03-07. http://www.attorneygeneral.jus.gov.on.ca/english/news/2008/20080307-dst-nr.asp. Retrieved 2010-09-21. 
  4. The specification for the Eastern Time Zone is set forth at 49 CFR 71.4, and is listed in Text and pdf formats.
    The boundary between Eastern and Central is set forth at 49 CFR 71.5, and is listed in text and pdf formats.
  5. McDearman, Brian (2006-08-13). . The Decatur Daily. http://legacy.decaturdaily.com/decaturdaily/news/060813/zones.shtml. Retrieved 2009-03-22. 
  6. http://www.diputados.gob.mx/bibliot/publica/inveyana/polisoc/horver/capitulo5.htm