The United States was once the country with the most developed railway construction in the world, so its railway gauge was adopted as the international standard gauge. The US railway gauge is 4 feet, 8 and a half inches, or 1.435 meters in metric system.
Since the United States was originally a British colony, the American railway gauge actually adopted the British railway gauge;
The British railway gauge came from the tram gauge in London, England; the tram gauge in London came from the wheelbase of British horse-drawn carriages;
London carriage
British nobles living in London in the 18th century often took carriages to their country estates. Therefore, the wheel spacing of British carriages at that time was naturally limited by the ruts of British country roads;
The center width of British country ruts was 4 feet, 8 and a half inches. It was not randomly determined, but came from ancient times. The wheel spacing of chariots prescribed by the Romans;
The ancient Romans determined their wheel spacing based on the chariots they used at that time;
Trains during the Industrial Revolution
The wheel spacing of Roman chariots was determined by the reasonable distance between the buttocks of the two parallel horses pulling the carriage when the carriage was moving forward. Width;
Since the industrial revolution started in the United Kingdom, they first built steam engines and railways. The United Kingdom is a conservative country that respects old traditions. Therefore, the reasonable width between the buttocks of the two running horses driving chariots in the ancient Roman era has become today's international standard railway gauge.
