Eastern Daylight Time (EDT), which is four hours behind Coordinated Universal Time (UTC−04:00) and observed during spring/summer/early autumn.
Areas in the Eastern Time Zone which do not observe daylight saving time use Eastern Standard Time. Observation of daylight saving time starts on the second Sunday in March, at 2:00 a.m. EST, clocks are advanced to 3:00 a.m. EDT, creating a 23-hour day. On the first Sunday in November, at 2:00 a.m. EDT, clocks are moved back to 1:00 a.m. EST, which results in a 25-hour day.[2][3]
The time in this zone is based on the mean solar time of the 75th meridian west of theRoyal Observatory, Greenwich.
The boundaries of the Eastern Time Zone have moved westward since theInterstate Commerce Commission (ICC) took over time-zone management from railroads in 1938. The easternmost and northernmost counties inKentucky were added to the zone in the 1940s, and in 1961 most of the state went Eastern. In 2000,Wayne County, on theTennessee border, switched from Central to Eastern Time.[4] Within the United States, the Eastern Time Zone is the most populous region, with nearly half of the country's population.
In March 2019, theFlorida Legislature passed a bill requesting authorization fromCongress for year-round daylight saving time, which would effectively putFlorida on Eastern Daylight Time year-round (except for west of theApalachicola River, which would be on Central Daylight Time year-round).[5] A similar bill was proposed for theCanadian province ofOntario byits legislative assembly in late 2020,[6] which passed though was placed on hold until Quebec andNew York agreed to make the same change, which had not happened as of 2024.[7]
For those in the United States, daylight saving time for the Eastern Time Zone was introduced by theUniform Time Act of 1966, which specified that daylight saving time would run from the last Sunday of April until the last Sunday in October.[8] The act was amended to make the first Sunday in April the beginning of daylight saving time beginning in 1987.[8] Later, theEnergy Policy Act of 2005 extended daylight saving time in the United States, beginning in 2007.[8]
Within Canada, as with the United States, the Eastern Time Zone is the most populous time zone. Most of Canada observes daylight saving time synchronously with the United States, with the exception ofSaskatchewan,Yukon,[10] and several other very localized areas.Southampton Island in Nunavut uses Eastern Standard Time throughout the year.[9]
Quintana Roo is the only Mexican state to observe Eastern Standard Time (Zona Sureste; Southeast Zone), after successful lobbying effort by tourism interests to move from Central Time.[15] Quintana Roo does not observe daylight saving time.
TheBahamas andHaiti officially observe Eastern Time with daylight saving time.Cuba generally follows the U.S. with Eastern Standard Time in the winter, and Eastern Daylight Time in the summer, but the exact day of change varies year to year. TheCayman Islands,Jamaica, andNavassa Island use Eastern Standard Time year-round.
TheTurks and Caicos Islands followed Eastern Time with daylight saving until 2015, when the territory switched to theAtlantic Time Zone. The Turks and Caicos Islands switched back to the pre-2015 schedule in March 2018.[16] A 2017 consultation paper highlighted the advantage for business and tourism of being in the same time zone as theeastern United States as an important factor in the decision.[17]
^The specification for the Eastern Time Zone is set forth at 49 C.F.R. § 71.4, and is listed intextArchived January 13, 2012, at theWayback Machine andPDFArchived January 14, 2012, at theWayback Machine formats. The boundary between Eastern and Central is set forth at 49 C.F.R. § 71.5, and is listed intext andPDF formats.