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History[ edit ] Prior to the adoption of four standard time zones for the continental United States, many towns and cities set their clocks to noon when the sun passed their local meridianpre-corrected for the equation of time on the date of observation, to form local mean solar time.
Noon occurred at different times but time Time zones between distant locations were barely noticeable prior to the 19th century because of long travel times and the lack of long-distance Time zones communications prior to the development of the telegraph. The use of local solar time became increasingly awkward as railways and telecommunications improved.
Each train station set its own clock making it difficult to coordinate train schedules and confusing passengers. Time calculation became a serious problem for people travelling by train sometimes hundreds of miles in a dayaccording to the Library of Congress.
Every city in the United States used a different time standard so there were more than local sun times to choose from. Time zones were therefore a compromise, relaxing the complex geographic dependence while still allowing local time to be approximate with mean solar time.
Railroad managers tried to address the problem by establishing railroad time zones, but this was only a partial solution to the problem. Four standard time zones for the continental United States were introduced at noon on November 18,when the telegraph lines transmitted time signals to all major cities.
The US time-zone system grew from this, in which all zones referred back to GMT on the prime meridian. It is ultimately the authority of the Secretary of Transportationin coordination with the states, to determine which regions will observe which of the standard time zones and if they will observe daylight saving time.
Only the full-time zone names listed below are official; abbreviations are by common use conventions, and duplicated elsewhere in the world for different time zones. The United States uses nine standard time zones.
As defined by US law  they are:The Time Zone Converter converts times instantly as you type.
Convert between major world cities, countries and timezones in both directions. Timeticker - The exact time of the world.
A full featured Multimedia-Site created with Flash by Martin Zwernemann. Have fun! Daylight Saving Time; Time Zone Abbreviations; Time Zone News; Time Tools Overview; Related Link.
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This is a list of time zones release c. The list is derived from the zones, links, and rules and the 7 "continent" – africa, antarctica, asia, australasia, europe, northamerica, and regardbouddhiste.com also includes other valid entries from the etcetera and backward files..
The four columns are mapped into columns 1–4 (marked with *) in the table below. A time zone is a region of the globe that observes a uniform standard time for legal, commercial, and social purposes. Time zones tend to follow the boundaries of countries and their subdivisions because it is convenient for areas in close commercial or other communication to keep the same time..
Most of the time zones on land are offset from Coordinated Universal Time (UTC) by a whole number. This is a time zones by US states. For more information about time zones, please see: time zone. Most of the United States uses Daylight Saving Time (DST). In the list, it will say if the state or territory does not use DST.