Originally built for commercial purposes, to link Salta and Chile, the Tren a las Nubes took 60 years to come to fruition from the time it was first conceptualized in 1888. Though the 38-hour journey was not popular with passengers and its freight transport didn’t have much luck, it remains legendary and is popular among tourists who have filled its cars to soar through the Quebrada del Toro since the 1970s.
Unfortunately, the train was suspended due to flood damage in 2005 and has not been running since. The current government is working to change all that, however, and in October 2007 it took to the tracks once again on a promotional journey. Argentines and tourists alike are hopeful that it will be back to its normal service some time in 2008. Until then, it remains a remarkable feat of engineering, and travelers can marvel at it along the parallel Route 51.
Construction of the railway began in 1921 under the direction of engineer Richard Fontaine Maury and it took 20 years in total due to weather conditions and other hazards. All that planning and toil created a 571-kilometer railway which starts in Salta, 1,187 meters above sea-level and reaches 4,475 meters at Abra Chorillos, its highest point. As the train climbs through the mountains it passes over and through 29 bridges, 21 tunnels, and 13 viaducts. The railway uses zigzag switchbacks and 360 degree loops that aid the train in gaining vertical elevation, but the biggest feat is La Polvorilla Viaduct, near San Antonio de los Cobres, which spans 224 meters and rises 63 meters high.
When running, the tourist train starts in Salta and ends at La Polvorilla, where it turns around to make the return journey. The trip lasts a full day, with very little time spent off the train. In October of 2007, it made a promotional journey, and its return to service is hopefully imminent. When service resumes, it will most likely begin with its previous seasons, April to October, but there has been talk of extending the season.