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Alamosa–Durango line

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The Alamosa–Durango line or San Juan extension was a railroad line built by the Denver and Rio Grande Western Railroad, following the border between the U.S. states of Colorado and New Mexico, in the Rocky Mountains. The line was originally built as a 3 ft (914 mm) narrow-gauge line between Alamosa, Colorado, and Durango, Colorado. Portions of the route survive to this day: the now standard-gauged segment from Alamosa to Antonito, Colorado, and a narrow-gauge portion from Antonito to Chama, New Mexico.

Alamosa–Durango line
Denver and Rio Grande narrow gauge freight near Chama 1968.JPG
Denver and Rio Grande freight train near Chama, NM, 1968.
Other name(s)San Juan extension / San Juan line
StatusPartially closed
LocaleColorado and New Mexico, United States
Durango (1881-1968)
Chama (1968-present)
Former connectionsRio Grande Southern Railroad
Rio Grande and Southwestern Railroad
Closed1968 (Chama-Durango)
Line length200.2 mi (322.2 km)
Track gauge4 ft 8 1⁄2 in (1435 mm) (Alamosa-Antonito)
3 ft 0 in (914 mm) (Antonito-Chama)
Old gauge3 ft 0 in (914 mm) (Alamosa-Durango)
Highest elevation10,015 ft (3,053 m)
Maximum incline4% (1 in 25)


The 200 mile rail line was built in the early 1880s to access the various mineral resources in south-western Colorado. In 1881, the line reached Durango and a short time later, a branch was built up the Animas river valley to the mining town of Silverton. In addition to the ore traffic, lumber and various agricultural commodities were also hauled along the route.

The 20th centuryEdit

When the D&RGW began the process of converting most of their mainlines to standard gauge in the early 1900s, the railroad had also planned to convert the San Juan extension. As a result, the section from Alamosa to Antonito was converted to dual gauge in 1901 with the addition of a standard gauge only branch from Durango south to Farmington, New Mexico a few years later. The D&RGW had also considered building a tunnel under Cumbres Pass which would have alleviated the steep 4% grade over the pass.[1] However, with the decline in ore traffic during the early 20th century, the railroad scrapped these plans and the Farmington branch was converted to narrow-gauge in 1923.[2] After World War II, the route experienced an unexpected "boom" in freight traffic due to growth in the oil industry around Farmington. This increase provided the necessary revenue to keep the line operating into the 1960s.

Abandonment and preservationEdit

By the mid-1960s, traffic had once again dwindled and in 1968, the D&RGW sought to abandon the entire route. As the D&RGW never introduced mainline diesel traction on their narrow-gauge lines, the Alamosa–Durango line eventually became of the last locations in the United States where steam locomotives were still in regular use. This brought recognition that all, if not, some portion of the line should be preserved as a museum or heritage railway. In 1970, a 64-mile segment between Antonito and Chama was purchased by the states of Colorado and New Mexico, and subsequently began operating excursion trains under the name of Cumbres and Toltec Scenic Railroad.

Meanwhile, the rest of the route from Chama to Durango, including the Farmington branch, was abandoned and the dual-gauge Alamosa–Antonito section was converted to a traditional 2-rail standard-gauge line, becoming the last 3-rail portion of the D&RGW system to be eliminated.[3]

The San Juan extension todayEdit

Portions of the Alamosa–Durango line survive to this day. The now standard-gauged section from Alamosa to Antonito remained under ownership by the D&RGW and its successor railroads until the line was sold to RailAmerica in 2003. Today, the line is part of the San Luis and Rio Grande Railroad, a class III railroad which also operates a seasonal excursion service.[4]

The narrow-gauge portion between Antontio and Chama continues to operate as the Cumbres & Toltec Scenic Railroad with two trains (one in each direction) traversing the route each day during summer months.[5]

At the ghost town of Pagosa Junction, also known as Gato, a small portion of narrow-gauge track along with a steel truss bridge are still in place.[6]

Tracks Across BordersEdit

Since the mid-2010s, the area along the now abandoned narrow-gauge portion between Chama and Durango has been in the process of being promoted as a scenic byway known as Tracks Across Borders. The byway, approved on April 16, 2015,[7] follows a series of US, State, and County highways through the communities in Colorado and New Mexico that the railroad once served.[8]


During the early years, freight trains over the Alamosa–Durango line were handled by the D&RGW's fleet of 2-8-0 steam locomotives while passenger services were worked by the railroad's 4-4-0 and 4-6-0 locomotives. In later years, these were gradually superseded when more powerful 2-8-2 type engines were introduced.[9]

Cumbres turnEdit

Because of the 4% grade on the west side of Cumbres Pass, most eastbound freight trains performed what was known as the "Cumbres turn". After arriving at Chama, a train would be broken up and hauled in sections up to Cumbres where it was then reassembled before continuing its journey. On other portions of the route, freights were operated either by double heading or with a helper engine (US) or bank engine[10] (Brit).

Branch linesEdit

The Alamosa–Durango line was host to several branch lines which diverted from various points along the route to connect nearby towns and industries. Among these were:

Silverton branchEdit

Opened in 1882, the 45-mile route from Durango to Silverton was built by the D&RGW to serve the mining industries in the San Juans. Almost abandoned in the 1960s, the branch was retained by the D&RGW to serve the tourist industry and the railroad operated a seasonal passenger service during summer months. In 1981, the route was sold to Charles E. Bradshaw Jr. who then operated the branch as the Durango and Silverton Narrow Gauge Railroad. The line is currently owned by American Heritage Railways.[11]

Santa Fe branchEdit

The Santa Fe branch, also known as the Chili line or Española branch, ran southwards for 125 miles from Antonito to Santa Fe, New Mexico. It was built by the D&RGW during the 1880s as part of a planned rail link with El Paso, Texas. However, construction didn't go beyond Española due to a dispute with the nearby Atchison, Topeka and Santa Fe Railway. In 1887, the last 35 miles from Española to Santa Fe was opened by the Texas, Santa Fe & Northern Railroad, a subsidiary of the D&RGW. The entire route was closed in 1941 and subsequently abandoned.[12]

Farmington branchEdit

When completed in 1905, the 47 mile Farmington branch was unusual in that it was built as a standard gauge line which resulted in Durango having dual gauge facilities. It was converted to 3 ft gauge in the 1920s after plans to standard gauge the Alamosa–Durango line fell through. This branch lasted until the late 1960s when the D&RGW ended its narrow gauge freight operations from Alamosa to Durango.[13]

Pagosa branchEdit

This branch was constructed in the late 1890s to serve the logging industry around Pagosa Springs. At 30.7 miles, this was the shortest of the D&RGW's major branch lines on the San Juan extension. It was also the shortest-lived; closure took place in the mid-1930s.[14]


  1. ^ Engineering News-record. McGraw-Hill. 1920.
  2. ^ "The Rio Grande Narrow Gauge". Retrieved 2018-05-19.
  3. ^ "DRGW.Net | The San Juan Extension". Retrieved 2018-05-26.
  4. ^ "San Luis & Rio Grande Railroad - Iowa Pacific Holdings". Iowa Pacific Holdings. Retrieved 2018-05-25.
  5. ^ Railroad, The Cumbres & Toltec Scenic. "Full Steam Ahead! Make 2018 Your Year to Ride the Cumbres & Toltec Scenic Railroad!". GlobeNewswire News Room. Retrieved 2018-05-25.
  6. ^ "PAGOSA JUNCTION, CO". Retrieved 2018-05-25.
  7. ^ "TABB-Byway-Fact-Sheet-052115.pdf" (PDF).
  8. ^ "Tracks Across Borders Scenic & Historic Byway | Colorado Scenic Drives on". Retrieved 2018-05-25.
  9. ^ "Denver & Rio Grande Western steam locomotives". Retrieved 2018-05-26.
  10. ^ "Alamosa to Chama". Archived from the original on 2018-05-27. Retrieved 2018-05-26.
  11. ^ "Train History | Durango & Silverton Narrow Gauge Railroad Train". Retrieved 2018-05-22.
  12. ^ "Chili_Line_Brief_History.pdf" (PDF).
  13. ^ "Farmington Branch". Archived from the original on 2017-07-03. Retrieved 2018-05-26.
  14. ^ "DRGW.Net | San Juan Extension – Pagosa Springs Branch". Retrieved 2018-05-22.