The Burro Mountain Railroad started out as a subsidiary of the El Paso and Southwestern Railroad (itself under the control of the Phelps-Dodge Mining Company) and established a 13-mile line from Burro Mountain Junction (at a connection with the Atchison, Topeka and Santa Fe Railway) to the town of Tyrone (at its original location). When Phelps-Dodge closed the mines at Tyrone down in 1924, the EP&SW sold the line to the Southern Pacific Railroad, who abandoned the line in 1933.
In 1952, Phelps-Dodge reopened the mines in Tyrone as open pit mines; the expansion of the mines forced Tyrone to relocate to its current location. In order to support their operation, Phelps-Dodge rebuilt the Burro Mountain Railroad, using much of the original right-of-way. The line continues in use today.
The Burro Mountain Railroad, albeit a small short line, is one of the few railroad lines that crosses the continental divide.
Thanks to Joe Gill for contributing information about this route.