Built in 1880 by the Baldwin Locomotive Works of Philadelphia for the three foot gauge Denver South Park & Pacific Railway (DSP&P) as number 51 this engine sports a Congdon smokestack designed to trap sparks thereby preventing range and forest fires. In 1885 the locomotive was renumbered 191 by the Union Pacific which then owned the DSP&P. In 1889 the engine was re-lettered to the Denver Leadville & Gunnison (DL&G) number 191 followed by lettering as Colorado & Southern (C&S) number 31 in 1899. Becoming surplus the engine was then sold to the Edward Hines Lumber Company for use on the Washburn & Northwestern Railroad (W&N) in northern Wisconsin and numbered 7. 1905 saw the engine sold again to the Robbins Lumber Company until 1919 when that company was bought out by the Thunder Lake Lumber Company where it worked until 1932 then placed on display at the Rhinelander Logging Museum. In 1973 it was repatriated to the Colorado Railroad Museum in Golden. In 2009 the engine underwent a cosmetic restoration in the Museum's roundhouse.