Trivia: The standard U.S. railroad width is directly derived from...

The standard U.S. railroad width (4 feet, 8.5 inches) is directly derived from the width of Roman war chariots. This is because the English expatriates who designed the U.S. railroad system based their measurements on the pre-railroad tramways built in England. Those tramways were built using the same tools used to build wagons, which were also that width. The reason wagons were built to that width is because otherwise, they would break during long treks across the old English roads. Those roads--built by the Romans--were full of ruts carved out by Roman war chariots. All Roman chariots were built to a standard width of 4 feet, 8.5 inches, and so English wagons were built so that their wheels would fit into those ruts.