At noon on Nov. 18, 1883, railroads in the U.S. and Canada began using a time zone system closely resembling what we use today. Before people used time zones, they allowed the passage of the sun to tell them what time was when. As travel times shrank exponentially thanks to the expansion of railroads across North America, that system became untenable.
Many towns dictated what clocks should be set at themselves, with over 144 local times in North America followed before the railroad companies instituted the new system. Passengers struggled to reconcile railroad timetables that gave conflicting information.
To resolve the issue, railroad companies agreed to create zones similar to what’s used today: the Pacific, Mountain, Central, and Eastern time zones. Decades later, the U.S. government officially adopted the time zones as World War I broke out, adding the Alaska time zone to the mix.
In 1966, time zone regulation was assigned to the Department of Treasury. To this day, the Secretary of Transportation can adjust the boundaries of a time zone under certain circumstances. Most recently that occurred in Mercer County, N.D., which in 2010 switched from Mountain to Central time.
You can read more about the creation on time zones in North America on the Bureau of Transportation Statistics website.
