I am reading Bill Cronon’s extraordinary Nature’s Metropolis. For obvious reasons, the chapters on credit, on canals and water transport, and on the railways are most interesting to me. This, however, came as a surprise:
Before the invention of standard time, clocks were set according to the rules of astronomy: noon was the moment when the sun stood highest in the midday sky. By this strict astronomical definition every locale had a different noon, depending on the line of longitude it occupied. When clocks read noon in Chicago, it was 11:50 A.M. in St. Louis, 11:38 A.M. in St. Paul, 11:27 A.M. in Omaha, and 12:18 P.M. in Detroit, with every possible variation in between. For companies trying to operate trains between these various points, the different local times were a scheduling nightmare. Railroads around the country set their clocks by no fewer than fifty-three different standards-and thereby created a deadly risk for everyone who rode them. Two trains running on the same tracks at the same moment but with clocks showing different times could well find themselves unexpectedly occupying the same space, with disastrous consequences.
And so, on November 18, 1883, the railroad companies carved up the continent into four time zones, in each of which all clocks would be set to exactly the same time. At noon, Chicago jewelers moved their clocks back by nine minutes and thirty-three seconds in order to match the local time of the ninetieth meridian. The Chicago Tribune likened the event to Joshua’s having made the sun stand still, and announced, “The railroads of this country demonstrated yesterday that the hand of time can be moved backward about as easily as Columbus demonstrated that an egg can be made to stand on end.” Although the U.S. government would not officially acknowledge the change until 1918, everyone else quickly abandoned local sun time and set clocks by railroad time instead. Railroad schedules thus redefined the hours of the day: sunrise over Chicago would henceforth come ten minutes sooner, and the noonday sun would hang a little lower in the sky.