Global Time Zones

global time zone map

A repetitive colour chart is used by the Global Time Zones Chart to define the different default time zones monitored in each state. The majority of them do not adapt their time zones observations and if they do so, it is highly likely that small border changes or changes in summer time compliance will be necessary.

You can see the actually observable time zones on the global time zones chart. Theoretically, time zones are theoretically divided into 24 time zones, each 15° long. It begins with the Universal Coordinated Time (UTC), generally known as Greenwich Mean Time (GMT), which is at the Greenwich meridian.

Greenwich meridian time is 7/12 degree south and 7/12 degree south of zero degree longitude. Timezones easterly of the Greenwich Meridian are later and timezones westerly of the Greenwich Meridian are sooner. For more details, take a look at our large-format global time zonecard.

These time zones show the distribution of the globe into 24 time zones, each 15° long. But if you look at this theory and try to match it with your real time use around the globe, you will find that there are many differences in the way time zones are actually observed by states.

World Time Zones, Global Time Zone(s) Map(s) & International Time Converter

Timezones were not necessary in the United States until railways made it possible to cover several hundred kilometers in one workday. Up until the 1860' most towns trusted in their own solar time, but this time it varied by about one per 12-mile trip either eastward or westward.

More than 300 tracing hours have been solved by setting up rail time zones. By 1883, most rail operators had trusted around 100 different but uniform time zones. This year, the United States was subdivided into four time zones centred approximately on the 75%, 90%, 105% and 120% channels.

On 18 November 1883 at 12 o'clock, cable wires sent the GMT time to the large towns, where the local government set their watches to the correct time for their area. The International Meridian Conference in Washington, D.C., on November 1, 1884, used the same procedures for zones around the United States. All 24 default Meridians, all 15 eastern and western of 0 in Greenwich, England, were referred to as Zonal Centres.

However, since some states, island regions and states do not want to be subdivided into several zones, the borders of the zones tended to migrate significantly from linear north-south routes.