In the 1960's the remaining Denver and Rio Grande Western narrow gauge line ran from Alamosa to Durango, with branches to Farmington and Silverton. It was an unusual operation in several respects. In addition to the novelty of being three foot narrow gauge, it was the last mainline steam operation in the U.S. , using steam until freight operations were abandoned in 1968. And trains operated over 10,000 foot Cumbres pass. Despite operating with an ancient car fleet of mostly wooden underframe cars dating back to the 1890's, it often ran long trains of 60-70 cars. Because of the long trains a lot of them had two engines.
When freight operations were abandoned two significant portions of the railroad survived as scenic tourist railways, the Durango and Silverton Narrow Gauge Railroad, and the Cumbres and Toltec Scenic Railroad, continuing the steam operation into the 21st century.
I first visited these lines in 1960 and photographed their last years of freight operations. And I have returned regularly since then to photograph the surviving tourist operations.
There are a lot of pictures in these galleries, the Personal Favorites gallery will give you the short version.