General Time Convention made station clocks legible

Before 1883, American towns and cities each set their clocks by local solar noon, producing well over a hundred distinct local times across North America. As railroads expanded rapidly after the 1860s, each line generally ran on the time of its home city or a major terminus, so by the early 1880s there were still roughly 80 different railroad time standards in simultaneous use, and a single train crossing several lines might cross nearly that many time changes.

Proposals to fix this had existed for over a decade — Charles Dowd published a four-zone national time plan in 1870, and Canadian railway engineer Sandford Fleming proposed a full international time standard in 1876 — but neither moved from paper to practice, because no single railroad had the authority to impose a standard on its competitors, and the industry collectively feared that pushing the issue into public view would invite a government solution they'd have no say in designing.

Railroads voluntarily reset station clocks to four time zones simultaneously, making the standard real because they controlled the schedules it governed.

Because the railroads were the ones setting and publishing the schedules the standard needed to govern, their own voluntary adoption was sufficient to make the new time zones real in practice — there

The approach only works when the entities whose voluntary agreement is needed are few enough, and motivated enough by a shared pain point, to actually coordinate — the roughly 80 railroad time standar

Any industry whose members are all individually harmed by a lack of a shared standard — a format, a unit, a protocol — but see no single company or regulator moving fast enough to set one, can convene

The four time zones railroads adopted in 1883 are, with only minor boundary adjustments, the same zones the United States uses today. The federal government did not formally codify them into law until the Standard Time Act of 1918 — 35 years after the industry had already made them the de facto national standard simply by using them.