(clock ticking loudly) - Once upon a time, time wasn't standardized, and that was a big problem for the booming railroad industry.

A problem that would be solved in Chicago in 1883.

Before a standardized time system was adopted in the United States, determining the time of day was a bit of a free for all.

(upbeat music) Each city set its clocks based on the position of the sun.

So noon in Chicago was different from noon in St.

Louis.

That meant there were more than 100 different local times across the country in the 19th century.

In Illinois alone, there were nearly 30 different local times.

But as railroads expanded rapidly, the problems with this became unsustainable, even dangerous, because every city kept its own time.

Railroad timetables were head-spinning, often listing multiple arrival and departure times for the same train.

(upbeat music) And it wasn't just a travel headache, it was also a matter of safety.

If railroads confuse the time, trains were at risk of colliding.

In 1883, one such crash happened when two passenger trains collided near Valley Falls, Rhode Island killing 14 people.

The two conductors watches were said to be off by two minutes.

(intense music) (gentle music) So it was high-time for a solution.

On October 11th, 1883, railroad companies came together for the general time convention at the Grand Pacific Hotel in Chicago.

The delegates ultimately established five time zones, each one hour ahead of the zone to its west.

Today, of course, we only have four.

A month after the convention on November 18th, 1883, the railroads implemented standard time on what was called "The Day of Two Noons".

At precisely noon, local time in Pittsburgh, the Allegheny Observatory sent a telegraph signal to railroads across the country and station agents reset their clocks to the top of the hour.

Finally, on time, meant the same everywhere.

Congress would later make railroad time the law of the land with the Standard Time Act of 1918, making four-time zones in the continental United States, a federal standard.

After half a century of railroading, America had solved the problem.

It was only a matter of time.

(gentle music)