Passage Three
The men who planned and constructed the first American railroads were men of great vision. They predicted that their “iron horses” would open vast expanses of land to farming and industry. They knew that towns would spring up along the new railroads. Yet few of these pioneers could have guessed that American railroads would establish the system of time used throughout most of the world today.
Until the 1880s, all time in the United States was sun time. Farmers set their clocks to noon when the sun appeared to be overhead. In towns, people set their clocks by a courthouse clock or factory whistles. One town’s time was often different from the time in a neighboring town.
As the new railroads expanded, large numbers of people began to travel. But the railroads were unable to print accurate timetables when most towns along their tracks have their clocks set differently. There was need for a change, and the railroads led in planning it.
In 1883, railroads in the United States and Canada adopted standard time, a system which divided the continent into four time zones. Within each zone, all railroad clocks were set to an identical time. When it was noon in the Eastern Zone, it was nine o’clock in the Pacific Zone. Railroad time signals were sent out by the newly-invented telegraph.
Standard time quickly spread. Traveling businessmen set their watches to correspond to the railroad clocks. Factories and schools followed the railroad’s lead. Soon, nearly everyone in the United States and Canada was using the four-zone time system – standard time.
Today, nearly all the world keeps standard time according to an international system of twenty-four time zones.

Implied but not directly stated: ___________.