On November 18, 1883, railroad clocks across much of the United States and Canada were reset to a single new design. The Pennsylvania Railroad's watches changed by one minute and three seconds; on the Intercolonial Railway's lines through New Brunswick and Nova Scotia, conductors' watches changed by forty-five minutes. By the end of that day, trains that had run for decades on one timetable were running on another.
Until that Sunday, there was no single agreed answer to the question of what time it actually was. Clocks had long since replaced the sundial; what varied was which clock set the local standard. Each city set its own clocks from its own meridian, and railroads ran on whichever of those standards suited a given stretch of track, so that by early 1883 fifty-three separate time standards governed trains and passengers across the two countries. Lines running on different standards met and traded traffic at roughly three hundred points, and in several places the railroad's own time differed from the surrounding city's mean time by more than half an hour.
Railway officials, meeting that April to settle unrelated business, took up a plan William F. Allen, secretary of the industry's own General Time Convention, had spent years refining: divide the continent into a handful of belts, each keeping one mean time tied to a meridian, with each boundary set wherever a railroad's own traffic made the switch practical. Fifty companies endorsed the plan that spring. On October 11, the Convention's member railroads met in Chicago and adopted it outright, setting November 18 as the day a majority of them would change at once, synchronized by a telegraph signal sent from the Allegheny Observatory in Pittsburgh at the instant of noon on the ninetieth meridian. Some New England lines had already made the switch that October; the most recent adopter, the Union Pacific Railway and the city of Omaha, did not change until the following May.
The changeover reset roughly twenty thousand station clocks and three hundred thousand employees' watches in a single day. No government compelled any of it. By the time Allen wrote about the reform the following year, more than eighty percent of American cities with over ten thousand residents had adopted the same four standards on their own, for no better reason than that the railroads already ran on them and everyone else's business ran on the railroads. Congress did not write standard time into federal law until 1918, thirty-five years after the industry had settled the question itself. Allen himself could not find a single accident anywhere that the switch itself had caused.
A timetable is a promise about one fact: what time a train will reach a given place. Fifty-three competing clocks had not made that promise false. They had made it impossible to check, since no two readers of the same schedule could be sure they meant the same hour by it. The clocks of 1883 did not get more accurate. The country agreed, for the first time, on what accurate meant.