The Denver and Rio Grande Railroad, opened in 1871, was one of the first three narrow gauges in the United States and by far the longest and most significant. It effectively circled the state of Colorado, and feeder lines were run to the mining communities of Leadville, Aspen, Cripple Creek, Telluride and Silverton. Through affiliated companies, its lines extended west to Salt Lake City, Utah and south to Santa Fe, New Mexico. The northern trunk line was re-gauged to standard early, but the southern portions remained steam hauled and narrow gauge until the 1960s.
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