How far apart are the two rails from inside to inside for standard guage North American railways?

Question

How far apart are the two rails from inside to inside for standard guage North American railways?

Answer 1

4 feet 8 and one half inches

Answer 2

Michael S. is right. The origin of that gauge is still a mystery. We know it came from England. But no one is sure why that measurement was decided on. There were many other gauges in the U.S. in the past, although 4' 8.5" was the most common. Before 1900, there was a 2' railroad in Maine. Many 3' lines, usually in difficult terrains. Some 30 inch industrial lines. And a 5 foot gauge in TN before the Civil War.

Answer 3

When railways were first started, they converted the existing road wagons for carraige purposes. Wagons had their wheels set four feet eight and a half inches apart and it was that width that became the standard gauge.

However, it was Brunel who realised that the standard gague was not the optimum gague either for speed or passenger comfort. So he developed the seven foot broad gague. Sadly, his gague was abandoned in the fight for uniformity.

If the broad gague had been adopted, then it would have been easier to develop and operate modern high speed trains.