The Manitou & Pikes Peak Cog Railway, opened in 1891, provides an access to the famous mountain in Colorado. It starts in Manitou Springs at an elevation of 6,320 ft (1,930 m) and reaches the top at 14,115 ft (4,302 m). While its steepest section has a gradient of 25 percent, the average is twelve percent. All of its steam locomotives were built by Baldwin, with No. 6 being delivered in 1906.
No. 6 was the first one to be fired with oil. After its older sisters were rebuilt as four-cylinder Vauclain compounds, it was built this way and had its axles turned by levers instead of direct connecting rods. The boiler and the cab were inclined by 16 percent to compensate for the gradient. As opposed to most of its sisters, it is not preserved today since it was scrapped in 1955.