The "Roman cart track" story has never been able to be verified (although it was researched by alt.folklore.urban a few times :-). This from... http://www.truthorfiction.com/rumors/railwidth.htm Where did the four-foot, eight-and-a-half-inch standard originate? Gabriel says it was from a Englishman named George Stephenson. Carts on rails had been used in mines in England for years, but the width of the rails varied from mine to mine since they didn't share tracks. Stephenson was the one who started experimenting with putting a steam engine on the carts so there would be propulsion to pull them along. He had worked with several mines with differing gauges and simply chose to make the rails for his project 4-foot, eight inches wide. He later decided that adding another six inches made things easier. He was later consulted for constructing some rails along a roadway and by the time broader plans for railroads in Great Britain were proposed, there were already 1200 miles of his rails so the "Stephenson gauge" became the standard. Interestingly, the 4-foot, eight-and-a-half inch width has not always been the standard in the U.S. According to the Encyclopedia of American Business History and Biography, at the beginning of the Civil War, there were more than 20 different gauges ranging from 3 to 6 feet, although the 4-foot, eight-and-a-half inch was the most widely used. During the war, any supplies transported by rail had to be transferred by hand whenever a car on one gauge encountered track of another gauge and more than 4,000 miles of new track was laid during the war to standardize the process. Later, Congress decreed that the 4-foot, eight-and-a-half inch standard would be used for transcontinental railway.