Its the distance between the rails
It varies from 2 feet to over 10, in the USA it's usually 4 feet 8 & 1/2 inches,
there is a tiny bit of 3 foot trackage in the US.
Adopting standard-gauge tracks was important for the railroad industry because then railroad cars could be switched from one track to another for more efficient service. The standard size of railroad cards after this action made it possible for railroads to join forces to move products.
Depends on the railroad, but the most common was 33 feet lengths - same as standard gauge.
The standard gauge of railroad track was established by the US Congress on March 3, 1863 at four feet, eight and one half inches. It was not adopted in 1886 and it is still that dimension.
Adopting standard-gauge tracks was important for the railroad industry because then railroad cars could be switched from one track to another for more efficient service. The standard size of railroad cards after this action made it possible for railroads to join forces to move products.
There are approximately 233,000 miles of railroad track in the United States and back in 1840 there were 21,000 miles of railroad track
Nevada County Narrow Gauge Railroad was created in 1874.
Nevada County Narrow Gauge Railroad ended in 1943.
Standard North American railroad tracks are 54.5 inches apart. This distance is known as the gauge of the rail.
The standard gauge of railroad track in the US was established by the US Congress at four feet, eight and one half inches on March 3, 1863, not in 1886.
It doesn't require to be capitalized.
Railroad
Rail gauge is the distance between the inner sides of the two parallel rails that make up a railway track. Sixty percent of the world's railways use a gauge of 4 ft 8½ in (1,435 mm), which is known as the standard or international gauge. Gauges wider than standard gauge are called broad gauge, those smaller are called narrow gauge. Some stretches of track are dual gauge, with three (or sometimes four) parallel rails in place of the usual two, to allow trains of two different gauges to share the same path.