Within the United States, the Eastern Time Zone is the most populous region, with nearly half of the country's population. In 2000, Wayne County, on the Tennessee border, switched from Central to Eastern Time. The easternmost and northernmost counties in Kentucky were added to the zone in the 1940s, and in 1961 most of the state went Eastern. The boundaries of the Eastern Time Zone have moved westward since the Interstate Commerce Commission (ICC) took over time-zone management from railroads in 1938. Southern parts of the zone in Panama, Colombia, Peru, Ecuador, and the Caribbean, however, do not observe daylight saving time. EST, which results in one hour being duplicated. On the first Sunday in November, at 2:00 a.m.
On the second Sunday in March, at 2:00 a.m. Eastern Daylight Time ( EDT), when observing daylight saving time (spring/summer), are four hours behind Coordinated Universal Time ( UTC−04:00).Eastern Standard Time ( EST), when observing standard time (autumn/winter), are five hours behind Coordinated Universal Time ( UTC−05:00).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. The time change in the USA always takes place at 2 o'clock of the respective local time.DST is observed in parts of this time zone. Unlike Europe, for example, the clock is turned on the same night, but not at the same time. Only Hawaii and most of Arizona remain on standard time all year. It always begins on the second Sunday in March and ends on the first Sunday in November. Today, daylight saving time is introduced on the same day throughout the country. However, it was not implemented until 1918 during the First World War. Daylight Saving Time in the USA Earlier than in most other countries, daylight saving time was introduced by Benjamin Franklin in 1784. Together with Wake Atoll (UTC+12), they are on the other side of the International Date Line. Guam and the Northern Mariana Islands are in Chamorro Time (UTC+10).American Samoa received its own time zone, which today also includes the atolls Midway and Palmyra, as well as Kingman Reef.Puerto Rico and the American Virgin Islands with Atlantic Time.Outside these areas, there are other territories of the USA with their own time zones as well: Later, Alaska and Hawaii also got their own time zones. In northern Arizona, there are even areas that don't even switch to daylight saving time.
As many as 14 of the 50 states have two time zones.