Standard Time.

At the Clock and Watch museum, you not only get to see a whole lot of clocks and watches, but you get to find out some odd things about time measurement and the history of calendars.

Did you know that in Japan they used to use variable length hours? They changed as the season changed. Clocks were VERY difficult to build there.

The original water clocks were built to limit the length of politician's speeches. Some long-winded speakers would not pour in clean water at the start of their speech, but would use water from a well that had a lot of silt in it so that the water would flow slower.
That is where the term "don't muddy the water" came from.

The oddest thing to me was some American history that wasn't too far in the past.
We have Eastern Standard Time (EST), Pacific Standard Time (PST), CST, MST.
Well, there are twenty four of them around the world. Obvious after it's stated, isn't it?

Well they still argue about daylight savings time, but they used to argue about Standard time too. Every town had it's OWN noontime. When the sun was directly overhead.
Every town. Not just the big ones. That worked fine. Most watches weren't that accurate and you didn't travel fast enough that anything seemed askew. You would just adjust your pocket watch to match the local time.

Then the trains started running. Time wasn't an issue when a train line only had one train that went one way to the end of the track, and then went the other way, but trains became popular and more were built. They started using the same tracks to go both ways ... at once.
Spectacular collisions with large explosions from large boilers became common.

They needed to use a consistent time value.
Railroads developed "Railroad Time".
Each railroad company would synchronize ALL of their stations to the local time of the city that the main office was in. Each railway station had clocks that showed the "Local Time" and the "Railroad Time". The "Railroad Time" was transmitted by telegraph so that they were consistent.

Trains could now coordinate when they should pull into a siding to let a train going the other way on the same tracks, actually go the other way without the nasty interruption of an explosion and dead people. The quantity of train wrecks went WAY down after "Railroad Time" was adopted.

Then the various railroad companies started connecting their tracks to other railroad companies. For a while there were conversion tables so you could subtract 2 hours, 19 minutes and thirty seconds from the Denver railroad to know when the Chicago railroad was going to be at ten o'clock. They had used the same type of conversion charts back in the old days to convert from "town time" to "other town time" with very limited success. These charts were worse.
East-West wasn't the problem, it was which BRAND of train was coming through.

Train crashes were becoming much too common. The price of equipment meant that a single crash could ruin a month's profits, and if there were several crashes..... well, something had to be done.

The railroad tycoons developed standard time at about the same time that Europe was running into the same issues. Some people wanted 24 time zones, some wanted none. If we had time zones, where do they start? Greenwich had become a stepping off point for many of the conversion charts over there, so it was decided that worldwide standard time would be Greenwich minus your timezone. Except France. France wanted the standard time to be in Paris. So for a great number of years there was worldwide standard time, and then "Paris Time" which was some hours, nine minutes, and 12 seconds different from Greenwich Mean Time.
Years later, when one central office was needed to coordinate the correction input from all the different areas of the world, Paris was chosen as the spot. At that point France finally adapted Greenwich Mean Time and synchronized their clocks with the rest of the world.

And America? The trains were already running on time with a lot less booms.