d for daylight

The Eastern Time Zone (ET) is a time zone encompassing part or all of 23 states in the eastern part of the United States, parts of eastern Canada, and the state of Quintana Roo in Mexico.

Places that use:

Eastern Standard Time (EST), when observing standard time (autumn/winter), are five hours behind Coordinated Universal Time (UTC−05:00).
Eastern Daylight Time (EDT), when observing daylight saving time (spring/summer), are four hours behind Coordinated Universal Time (UTC−04:00).On the second Sunday in March, at 2:00 a.m. EST, clocks are advanced to 3:00 a.m. EDT leaving a one-hour gap. 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 one hour being duplicated. Southern parts of the zone in Panama and the Caribbean, however, do not observe daylight saving time.

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