The Standard Time System in the United States

At Chicago’s Grand Pacific Hotel, on the site of the present Continental Bank building, the General Time Convention of 1883 adopted the current Standard Time System in the United States on October 11 of that year. Called by the nation’s railroads, the convention sought a better and more uniform system to govern railroad operations, replacing a method in which time was determined by the position of the sun, with high noon as the only exact local standard, producing more than 100 different local times. The new plan, proposed by William F. Allen, the convention secretary, established four equal time zones across the country, each one hour ahead of the zone to its west, with railroad clocks in each zone synchronized to strike the hour simultaneously. The system began on November 18, 1883, a Sunday known as the Day of Two Noons, when the Allegheny Observatory at the University of Pittsburgh transmitted a telegraph signal at exactly noon on the 90th meridian and railroad clocks throughout the United States were reset by time zone. Though first implemented by the railroads, the federal government, states, and cities began using the system almost immediately, and Congress formally acknowledged it by passing the Standard Time Act on March 19, 1918.

Chicago, Illinois · United States