In the late 1880s, William Jackson Palmer and his Denver and Rio Grande (D&RG) West Railroad had big dreams of conquering the Rocky Mountains to tap into the wealth flowing in and out of the new mining districts. Railroad companies knew building tracks through the mountains would be challenging and expensive.

Narrow gauge trains and tracks had been in limited use since 1865. These tracks, with 36-inch rail width instead of the standard 56 1/2-inch, would be cheaper and could better maneuver ...