When and why were time zones established?

Earth is divided into 24 time zones so that everyone in the world can be on roughly similar schedules. Until about 100 years ago, each city set its clocks to local time. Noon was the time when the Sun was at its highest in the sky, as viewed from that city. In order to make this happen, however, even neighboring cities needed to set their clocks differently. For example, when it was 8:00 in New York City, it was 8:12 in Boston (because Boston is about three degrees east of New York). Before modern transportation and communication, this time difference did not really affect society. As railroads were being constructed in the late 1800s, however, the Canadian railway planner and engineer Sir Sandford Fleming proposed a world time zone system. He did this so that train schedules could be written using common time settings. In November 1883 the U.S. and Canadian railroad companies instituted standard time in time zones. (Standard time in time zones was established by U.S. law with the Standard Time Act of 1918.) The concept was soon adopted internationally, with the world being divided into 24 time zones, each one a long strip from North Pole to South Pole, about 15 degrees of longitude wide. All the people in one time zone set their clock the same way, to the local time in the center of the time zone. Today, most countries use this time zone system.