How the World Agreed on the Time

For most of human history, every town kept its own time, and no one thought this strange. Noon was simply the moment when the sun stood highest in that particular sky, and the town clocks were set to match. Since a place a little to the east saw the sun reach its peak a few minutes earlier than a place to the west, neighbouring towns ran on slightly different times; but when the fastest way to travel was a horse, a difference of a few minutes between one town and the next was of no importance to anybody. A traveller might reset a pocket watch on reaching a new town, if the difference was even worth noticing, and life ran comfortably by the rhythm of the local sun. The very idea that distant places ought to share the same time would have struck most people as pointless, if not absurd.

The railways changed everything. Trains moved far faster than anything before them, and they ran to timetables that had to be obeyed to the minute. If every station along a line kept its own local time, a timetable became a nightmare to read and, worse, a danger: two trains running on clocks that disagreed could find themselves on the same stretch of track at the same moment. As accidents and confusion multiplied, it became clear that the growing railway networks needed a single, shared time. The problem was not merely one of convenience. A guard reading a timetable, a signalman clearing a line and a driver deciding when to depart all had to agree on the hour, and any disagreement between their clocks could send two trains hurtling towards the same point on a single track.

The railway companies themselves supplied the solution. In Britain they adopted one uniform standard, taken from the Greenwich observatory in London, and spread it along their lines, a system that became known as railway time. The electric telegraph, which could carry a signal down the wires almost instantly, made it possible to distribute the correct time from a central clock to distant stations, so that for the first time places hundreds of kilometres apart could be made to agree on the hour. Great railway stations began to display a single official clock, and the time it showed, carried down the wires from the observatory, gradually became the time of the surrounding town as well, whether the townsfolk had asked for it or not.

Across the Atlantic, the same problem was solved on a larger scale. In 1883 the railroads of the United States and Canada agreed to divide the continent into a handful of broad time zones, within each of which all clocks would read the same, jumping by a whole hour at the boundaries between them. This tidy arrangement, invented for the convenience of the railways, is essentially the system of time zones the whole world still uses today. The scheme was elegant precisely because it was simple: within each broad band everyone kept the same time, and only at the borders did the clocks jump, so that a traveller crossing the continent had to change a watch just a handful of times rather than at every station along the way.

The final step was international. In 1884 delegates from many nations gathered at a conference in Washington and agreed to measure the world's time from a single line, the meridian passing through Greenwich, which was chosen as the prime meridian from which all longitude and all time zones would be counted. Not everyone welcomed these changes; some towns clung stubbornly to their old local time for years, resenting a schedule that seemed imposed from far away. But the logic of a connected world was overwhelming, and the clock on the wall, once a purely local affair, had become part of a single global system. In time even the most reluctant communities fell into step, for a farmer or a shopkeeper who wished to catch a train, send a telegram or read a national newspaper had little choice but to live by the same clock as everyone else. The sun still rose when it always had, but the hour on the wall now belonged to the world. What had begun as a practical fix for the railways ended as one of the quiet revolutions of modern life, binding together distant strangers who would never meet but who could now, at last, agree on exactly when to meet. Few inventions have reshaped daily experience so completely while attracting so little notice.