Tennessee Pass (Colorado)
|This article needs additional citations for verification. (February 2011)|
Summit of Tennessee Pass along U.S. Highway 24, showing the memorial to the 10th Mountain Division
|Elevation||10,424 ft (3,177 m)|
|Traversed by|| US 24
Denver and Rio Grande Western Railroad
|Location||Eagle / Lake counties, Colorado, U.S.|
|Topo map||USGS Leadville North|
The pass traverses the continental divide north of Leadville in a gap between the northern end of the Sawatch Range to the west and the northern end of the Mosquito Range to the east. It connects the headwaters of the Arkansas River to the south with the upper valley of the Eagle River (in the watershed of the Colorado River) to the north. The pass is traversed by U.S. Highway 24, allowing access between Leadville and Interstate 70 in the Eagle Valley. The pass has a gentle approach on both sides with few steep gradients and no major hairpin curves. The summit of the pass is nearly level. The road over the pass is generally open all year round, easily negotiable by most vehicles, and closes only during severe winter storms.
The summit of the pass is the location of Ski Cooper, a ski area in the San Isabel National Forest operated by permit from the United States Forest Service. Most of the area is above the tree line, providing a panoramic view of the peaks of the Sawatch Range to visitors. The area was formerly a World War II training ground for United States Army troops of the 10th Mountain Division from nearby Camp Hale. A memorial to troops of the division is located at the summit of the pass.
The Denver and Rio Grande Western Railroad constructed a narrow gauge railroad over Tennessee Pass in 1881 as part of their extension to Aspen in order to compete Colorado Midland's standard gauge route to the mining area. In 1890, a new standard gauge line was built from Pueblo, to Grand Junction, and jointly with the Colorado Midland Railway, a tunnel was constructed about 200 feet (61 m) below the summit. In 1945, the original Tennessee Pass Tunnel was replaced by a newer tunnel. The line was the highest active mainline railroad mountain pass in the United States.
Once the Moffat Tunnel and Dotsero Cutoff were constructed, the line through Tennessee Pass became a secondary route. The Moffat Tunnel route had a maximum grade of 2%. The west side of the Tennessee Pass route has grades up to 3%. However, the east side of Tennessee Pass has a maximum grade of only 1.4%.
The Denver & Rio Grande's acquisition and merger to Southern Pacific Railroad (SP) in 1988 made the Tennessee Pass route a preferred transcontinental route. SP had a central route from California through to Kansas via Donner Pass, Tennessee Pass and trackage rights on the former Missouri Pacific route from Pueblo, Colorado into Kansas. The Moffat Tunnel rail line remains in operation.
In 1996, Union Pacific Railroad (UP) bought Southern Pacific. The railroad preferred the route via the Moffat Tunnel instead for routing traffic. The last revenue train went over Tennessee Pass in 1997. Soon after Union Pacific ran this last train, they applied to the STB for permission to abandon the line. The filing has since been withdrawn from further approval from the STB.
Currently, the line is not of much use as the former Missouri Pacific line to Pueblo has been partially abandoned so trains would have to travel from Denver, Colorado down to Pueblo, Colorado before heading west.
On July 10, 2012, part of the original 1890 tunnel collapsed, creating a sinkhole that damaged U.S. Highway 24 and forced its temporary closure between Redcliff, Colorado and Leadville, Colorado. The 1945 tunnel was not damaged. 
- "Tennessee Pass". Geographic Names Information System, U.S. Geological Survey. Retrieved 2011-02-05.
- "Old railroad tunnel collapses along Highway 24". 9News. 2012-07-10. Retrieved 2012-07-20.
- "100-Year-Old Railroad Tunnel Collapsed Below Sinkhole".