Fact: The normalized distance between the rails of railroad in the United States is 1.435 m (4 '- 8 ½ "). Why this distance so special is it used?
Because this is the way that railroads were built in England, and it is the English settlers who designed the railroads in the United States.
Why is it that the English were making them that way?
Because the first rails were built by the same people who built the rails for streetcars, and that was the distance they used.
Why did they use so that distance? Because the people who built the tramways used the same tools as those for building wagons, which had that wheel spacing.
Why do they have the carts that wheel spacing?
Because if they had used any other spacing, the wheels of the carts have tended to break down some long roads of old England as it was the spacing of the ruts. But who built these old roads?
Empire Rome built the first long road to Europe (including Britain) to transport their legions. These roads have been used since.
And what about the ruts on the roads?
The original ruts, to which all others were adapted for fear of destroying their wagon wheels, were formed by Roman war chariots. Moreover, since the carts were built for or by the Roman Empire, they were all identical in terms of wheel spacing. Therefore, we have the answer to the first question: Spacing Standard 4 '- 8 "½ U.S. railroads from the original specification of the war chariots of the Roman Empire.
The moral of this story: Specifications and bureaucracy are eternal.
The next time you have before you a standard / procedure / specification and you wonder "what asshole (horse's ass) happened with that?" you may well have been right. Indeed, the chariots of the Roman Empire were built to be just large enough to accommodate the later of two war horses (two horses' asses). But what does this have to do with space exploration?
There is an interesting extension of the history of railroads and later horses. When you see a space shuttle ready to fly, there are two large rockets attached to the sides of the main fuel tank. These are the boosters or SRB (Solid Rocket Booster). The SRB are made by Thiokol at a factory in Utah. The engineers who designed the boosters might have preferred them a bit bigger, but they must be handled by train from the factory to launch site. 
The railway between the plant and the launch site goes through a tunnel in the mountains. The SRB must be able to pass through this tunnel. The tunnel is barely wider than the railroad, and the track is about as wide as two horses later. We can therefore say that a major characteristic of what is unquestionably one of the modes of transport the most advanced in the world has been determined there are over 2000 years ago by the width of a horse's ass ...
"And You Thought Being a horse's ass wasn't important? Ancient horse's asses control Almost Everything ... & the current Horses Asses are controlling in Washington Everything Else! "
Original version in English
I do not know if the story is true, but it makes sense and is fun!
