former American railroad chartered in 1870 as the Denver and Rio Grande Railway (D&RG). It began with a narrow-gauge line extending from Denver, Colorado, south to New Mexico and west to Salt Lake City, Utah. Conversion to standard-gauge track began in 1888. In 1930 the D&RG took possession of the Denver & Salt Lake line (formerly Denver, Northwestern & Pacific Railroad), thereby acquiring the assets of a rail transit system created by David Halliday Moffat (Moffat, David Halliday). These included the Moffat Tunnel, which honoured Moffat posthumously for his vision of building a tunnel under Colorado's Continental Divide. Opened to rail traffic in 1928, the Moffat Tunnel shortened the trip between Denver and Salt Lake City by eight hours, placing Denver on a transcontinental route for the first time.

The railroad operated along more than 3,000 miles (4,800 km) of track between Missouri and Utah and was noted for its scenic passenger routes, which became part of Amtrak in 1983. The D&RGW derived much of its freight revenues from bituminous coal and lignite. It was absorbed by the Southern Pacific Rail Corporation (Southern Pacific Railroad) in 1988.