The first part of the line from Salida, CO, up to Malta (near Leadville?) was constructed as part of the narrow gauge extension of the Royal Gorge Route route in 1880. From Malta, what would become the Blue River Branch was run up to Leadville?, and then up and over Fremont Pass at 11,330 feet. The branch then worked down the north/east side of the pass as far as Robinson. Another branch was extended north to charcoal ovens at Crane’s Park, near the south side of today’s Tennessee Pass. The objective was not to cross the Divide and reach points west (that goal having already been accomplished via Marshall Pass), but rather to tap the mining boom under way in Leadville.
The next year, 1881, was more of the same. The branch from Malta to Cranes Park was extended over the Divide at Tennessee Pass, and then down the Eagle River valley/canyon to Red Cliff to serve a new pocket of silver mining. 1882 brought two more miles from Red Cliff to Rock Creek. Aside from more spurs around Leadville, the line over Tennessee essentially stayed the same until 1887.
By late 1886, a new silver boom was starting near Aspen, CO. The race was on between the Colorado Midland and the Denver & Rio Grande to see which road would tap the new mines first. The D&RG completed all 104 miles of the new narrow gauge line west from Red Cliff, through Glenwood Canyon to Glenwood Springs, CO, and then back up the Roaring Fork to Aspen (the Aspen Branch) by the end of 1887, handily beating the Colorado Midland.
In addition to silver, the new branch tapped a few coal mines, providing fuel for the smelters at Leadville. In order to accomodate these coal trains, a short three mile spur was built on the north side of Leadville, to connect the new line with the town. This avoided dropping all the way down to Malta and then needing to climb the grade back up.
As part of the Rio Grande’s massive efforts between 1888 and 1890 to construct a standard gauge mainline across the mountains, the Tennessee Pass route became the obvious choice. Most of the route was suitable to direct conversion – meaning curvature and gradient was well in line with standard gauge practices. The section over Tennessee Pass, however, would need to be reworked. Sources vary on how far on each side of the summit things were realigned1, but the most substantial improvement was at the top. In 1889-1890, the first Tennessee Pass tunnel was bored under the Divide, 200 feet lower than the original crossing. Initially, narrow gauge rails were run through it until the rest of the route was ready for standard-gauging. By late 1890, the section from Salida to Malta had been converted to dual gauge track, so as to not leave the Blue River Branch as an isolated narrow gauge chunk. Everything west – Tennessee Pass, Glenwood Canyon, and the Aspen Branch – was subsequently converted to pure standard gauge by the end of the year.
The Rio Grande quickly found that it was nearly impossible to get helpers back to Minturn in a timely fashion. Lacking both signals and radio contact with trains, granting permission for movement was so coarse that a single train could tie up a huge section of railroad. In 1903, the Grande put in a second main from Minturn to Rex, which was then extended to Red Cliff in 1907, Pando in 1909, and Deen in 1910. However, the Pando (aka Deen) Tunnel area provided an obstacle to continued construction of the double track – there simply wasn’t room.
The 1920s were a boom era for the Grande, and once again Tennessee Pass was a significant bottleneck. Recognizing that the largest productivity gains were to be had in the single-track sections, the Rio Grande installed 6.8 miles of Centralized Traffic Control (CTC) signalling between East Tennessee Pass and the beginning of double track, just past the Pando Tunnel. One long siding was added in the middle – 2.6 miles of track between East and West Mitchell. This was the first CTC installation west of the Mississippi, and the Rio Grande’s first step into signals. Also in 1928, those sections of the line not outfitted with CTC were given Automatic Block Signals (ABS).
In 1945, a new, larger Tennessee Pass tunnel was constructed, replacing the original tunnel constructed in 1890. The new tunnel was just geographically west of the original tunnel (by probably 50 feet or so). Also, at some pointThe old tunnel remains today, though both portals have been covered with dirt so as to prevent entry. On the south end, part of the original timber portal can now be seen sticking out of the dirt.
The next major change came in 1958. With dieselization complete, not as many helpers would be needed, alleviating some of the traffic between Minturn and the summit. Also, installations of CTC elsewhere on the Grande had convinced the railroad of its worth in keeping traffic moving. So, much of the second main from Minturn to Deen was pulled up and replaced with long sidings, and the entire stretch was placed under CTC control. This, along with the Kobe-Tennessee Pass and Minturn-Avon stretches, marked the last sections of the D&RGW mainline to come under CTC.
Tennessee Pass was a tough, and therefore costly, railroad to operate. With 3%+ grades on the west side and frequently heavy snowfall, Tennessee Pass was inferior to the ex-D&SL Moffat Route crossing via the Moffat Tunnel. However, the saving grace of Tennessee Pass would be the Pueblo gateway onto the Missouri Pacific. With booming demand for Colorado’s cleaner coal in the 1970s and 1980s thanks to the Clean Air Act and the oil embargo, it only made sense to send the product over TP and directly to Pueblo for interchange with the MP, rather than going via the ex-D&SL Moffat Route and then down the Joint Line?. However, many, including 1980s Rio Grand President WJ Holtman, argued that having two mainline crossings of the Divide was more than the Rio Grande could really afford.
1987 was the first time the powers that be attempted to shut down Tennessee Pass. Having successfully routed nearly all traffic via the Moffat (which pushed the Moffat Tunnel to near capacity), only two trains per day were left going over Tennessee. The experiment would be short-lived, however.
Philip Anschutz and Rio Grande Industries? purchased Southern Pacific in 1988. Wanting to capitalize on the new, shorter, combined D&RGW-SP Central Corridor route from California’s Bay Area to points east, the additional traffic would be more than the Moffat could handle. In addition, some of the tunnels on the Front Range were known to have clearance issues with double-stacked containers. So, a furious effort was made to not only reactivate Tennessee, but bring it in line with modern mainline standards – heavier rail, new ties and ballast, and working on a few problem tunnels to improve clearance. By the end of 1988, the line was officially back from the threshold of death. In only about eight years, the line went from two trains per day between Minturn and the summit to as many as thirty (including light helper sets). Despite traffic having been built up to this level, the beginning of a very quick end was less than a year away.
On 11-Sep-1996, Southern Pacific and Union Pacific merged in order to survive the recently created super-competitor, BNSF. One of the touted cost savings of the merger would be the elimination of Tennessee Pass, since UP planned to route all traffic east out of Denver on an upgraded Kansas Pacific line. The UP (ex-MoPac) line east from Pueblo would then also be abandoned as well, eliminating UP’s own duplication between the ex-KP and the ex-MP lines east out of Colorado.
Only just shy of a year after the UP-SP merger, on 23-Aug-1997, the last through revenue train went over the pass. The train was OMIGV-19, a westbound unit taconite train with two units on the front and three in the middle. It departed Pueblo at 1125h and pulled into Minturn at 2005h. The last train over the top of the pass is questionable, but DRGW 3075 went over the top from the west side on 23 Dec 1997 with two gons for Malta, running back light.2 The Malta Local continued to run from Pueblo-Malta until 9-Mar-1999, and beyond that only a few work trains have plied the east side of the pass.
Today, only the very western end of the route is still active. From Dotsero-Glenwood Springs, CO, the route forms part of the modern Union Pacific main as part of the line from Denver via the Moffat Route and Dotsero Cutoff. A local out of Grand Junction runs east beyond Dotsero several times a week to the drywall plant at Gypsum, but that’s as far as any regular train steps onto the former Tennessee Pass line. From time to time, UP will store cuts of coal hoppers on the unused stretch between Gypsum and Wolcott, but these moves are irregular at best.
The line is no longer formally up for abandonment, but UP also has no intentions of reactivating it in the near future, either.