A Durango & Silverton Narrow Gauge Railroad (D&SNG) train proceeds along the rocky "Highline" ridge high above the Animas River Valley in La Plata County, Colorado. The D&SNG is a narrow-gauge railroad that operates 45.2 miles of track between Durango and Silverton in southwest Colorado. The route was originally opened in 1882 by the Denver & Rio Grande Railway to transport silver and gold ore mined from the San Juan Mountains. The line has run continuously since 1881, and some rolling stock dates to then. It is now strictly a tourist and heritage line hauling passengers and is one of the few places in the United States that has seen continuous use of steam locomotives. In March 1981, the Denver & Rio Grande Western sold the line, and the D&SNG was formed. Trains operate from Durango just 26 miles into the mountains in winter months and the full 45 miles to Silverton during warmer months. Photo by Carol Highsmith.