I have a class I teach that deals with time and the creation of “time” as we think of it, but this video is a pretty good primer for those that haven’t thought about it.
Time standardization wasn’t a thing until 1847, when the railways in England needed to simplify their scheduling. As the video points out, most towns set their clocks from the point the sun was the highest in the sky. But even in a small area like Britain, the difference between noon in Yarmouth and noon in, say, Penzance — a whole 120 or so miles from one side of the island to the other — is different. Train schedules necessitated time be “standardized” in Britain.
This is why the scheme was known as “railway time.” For those of you running games before 1847, there’s no time zones. There’s no fixed time save local; there were trains, however, and getting to a place when you thought you would was often problematic. You might wind up spending an evening on a railroad bench waiting for the next train because it left a few minutes before you arrived.
By 1855, all of Britain was on GMT (Greenwich Mean Time), but Time Zones as we know it didn’t come into being until 1883 when the American rail companies adopted the “one hour” time zone similar to what we know today. Most of the world was on some form of standardized time zones by 1900, but there were loads of local variations. In the US, actual implementation of the StandardTime Act was in 1918, so even those with Victorian or Wild West period games can work this in — it might be noon on the town clock, but it’s 11:45 on the rail platform.