Big Boys, also known as "Titans of the Wahsatch," are an extremely large model of steam train used in Colorado. They were constructed to climb the steep incline over the Wahsatch just east of Utah. The train was economical because it was efficient but also because it reduced or did away with the need for helpers along the incline, which was known as the "helper district." Historians speculate that the name "big boy" was written on the side of the boiler in chalk by one of the machinists, and inspired the name it carries today.
The Big Boy train in Colorado also made headlines in the 20th century. Amidst a coal strike in 1946, the 4005 model became one of few trains altered to burn oil instead of coal. The attempt failed, however, because the oil was not able to reach sufficient heat to produce the steam necessary to carry the weight of the train. The model on display in the Forney Museum of Transportation in Colorado also made the news when it was involved in an accident in which many people were killed. It was repaired before returning to service and in 1970 the owners donated it to the museum.
Another famous locomotive on display in the museum in Colorado is the Forney Locamotive 044-T. A porter built the original model in Pittsburgh, Pennsylvania, in 1897. These trains were called "Little Giants" and were in popular use at the turn of the century. Steam powered engines on the elevated railways lasted only a few years as they were replaced by the new electric powered engines. Manufacturers used the trains to haul natural resources across the country but also passengers in the Denver area, especially in the Lakewood, Golden and Denver Circle Railway.
The locomotives that ran on the Denver and Rio Grande Western Railroad, particularly the model number 315, also have a long history in Colorado. They were fundamental in the foundation of the development of the Florence and Cripple Creek railroad in the mining district. The locomotives transported passengers and freight between the mines, delivering coal and supplies to isolated areas. It was a popular long-distance train and is an example of the more compact and narrow steam-powered locomotives.