How Do Countries Determine Their Time Zones?

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Matthias Kulka / Corbis

Russia wishes it were smaller. No, it isn't about to shed any territory, but President Dmitry Medvedev has suggested that Russia reduce its number of time zones from 11 to four, arguing that the extreme time difference — in which western Russia wakes for breakfast just as eastern Russia climbs into bed — "divides" the country and "makes it harder to manage it effectively." Can Russia just change time zones like that? How are time zones determined anyway?

Before the adoption of standard zones, towns set their own local times. Life was slow; it didn't really matter if 12:07 in one town was 12:15 in the next hamlet over. But with the advent of railroads and their accompanying train schedules in the 19th century, people suddenly needed to know the exact time so they didn't miss their trains (and conductors needed to make sure that trains operating on the same track didn't crash). In 1883, the U.S. and Canada adopted a standard time system. The following year, delegates from 22 nations met in Washington to coordinate times across countries. They selected the longitudinal line that runs through Greenwich, England, as the standard from which they would measure (it had already been used by sailors for centuries). Every 15 longitudinal degrees, the time changed by an hour, thus creating 24 time zones around the world.

Over the years, governments have adopted, altered or ignored Greenwich Mean Time (GMT) as they saw fit. The U.S. didn't sign its time zones into law until 1918. China used to have five time zones, but in 1949 communist leaders reorganized the country under one zone. Part of western Australia made up its time zone halfway between two official ones. And then there's the state of Indiana, which under the U.S.'s 1918 law fell into the Central Time Zone category. But in 1961, the Interstate Commerce Commission changed the time-zone lines so that half of Indiana fell into Eastern Time (a fact which the state legislature promptly ignored).

In 1966, the U.S. Congress passed the Uniform Time Act, making daylight saving a national practice, but one that states could decide whether or not to observe. The first year, only 19 states participated in daylight saving. As the years passed, more states acquiesced to the Federal Government's daylight saving schedule — which was created for energy-saving purposes, with the idea that an extra hour of daylight in the winter would cause people to use less oil. Arizona never adopted the new time plan on the grounds that it was too hot out to "spring forward" an hour in the summer. Daylight hours don't vary much in Hawaii, and the tropical state has never needed the time plan.

Americans observed daylight saving, but they didn't like it. In 1972, after much protest, President Richard Nixon signed the so-called Indiana amendment, which allowed states straddling time-zone boundaries to exempt only part of themselves from daylight saving. The result left part of Indiana in Central Time, part in Eastern Time, part observing daylight saving and part observing standard time throughout the year. Indiana resumed observing daylight saving on a statewide basis in 2006, but it still has counties in both Eastern and Central Time.

If Indiana can have two time zones, there's no reason that Russia, 180 times larger and with many millions more people, can't change its clocks to please its easternmost citizens. Two years ago, the U.S. saved energy by starting daylight saving three weeks earlier. Nepal is 15 minutes ahead of India but an hour and 15 minutes behind China. Iran can't decide what to do about daylight saving; its parliament wants to observe it, while President Mahmoud Ahmadinejad says no. And in 2007, President Hugo Chávez set Venezuela's clocks forward 30 minutes, supposedly to make the country more productive. In the end, time really is relative.