Southern Railway in 1905 announced it was carrying out a $4 million Chattanooga building program that included a new train station as well as a new line into town from Lookout Mountain.
The new Terminal Station was to be built on South Market Street near Main at the site of the old Stanton House hotel.
The line from Lookout was necessary because, due to increasing train traffic, the old line on a narrow strip around the base of the mountain was no longer adequate. Its single track was overcrowded with trains coming along the original route from Nashville as well as up from New Orleans and Birmingham.
Because there was no space for a parallel line at the base of the steep Lookout bluffs, it was necessary to build a long tunnel through the end of the mountain. Mexican laborers were brought in for the dangerous tunnel work on the project that stretched 3,537 feet in the mountainside.
Workers on the tunnel tapped into a spacious cave that had been inhabited by Native Americans for thousands of years. The train tunnel had the effect of sealing off the original entrance to the cave. Later, there was an attempt to drill down to the old cave from above, and it was then that Ruby Falls was discovered above the level of the sealed cave.
The new line branched off from the Nashville route near Wauhatchie Pike in Lookout Valley. It then proceeded to the Terminal Station using a string of concrete overpasses that extended from the valley to St. Elmo and then Alton Park.
The new line trestled over the old one near Cummings Highway, then it went across the highway on the first of the overpasses near where Wauhatchie Pike meets Cummings Highway..
It then went across the old Cummings family farm known as Cummings Bottom. A second concrete overpass was built across a dirt section of the old Federal Road that was built into the Indian Country in 1805. There are several more overpasses spanning dirt roads at Cummings Bottom.
The line trestles over Lookout Creek and then the old Nashville track before entering the tunnel below Cummings Highway behind the old Lockmiller's Motel.
It comes out near St. Elmo - still below Cummings Highway. There is a concrete overpass that spans Cummings Highway not far from the Mount Vernon Restaurant. In just a short distance, there is another overpass across St. Elmo Avenue. Then another one tops Tennessee Avenue.
There is an overpass above 37th Street, which follows the old Federal Road from Rossville. Another overpass is built above Alton Park Boulevard. The train then goes over the old TAG Railroad line and then over the extension that the Nashville line built to Alton Park.
It then follows an old Belt Line route into town on what has become a part of the Main Line at Chattanooga. It crosses Rossville Avenue and Main Street before reaching the rear of the Terminal Station.
The route now continues on along the Main Line by the National Cemetery and Warner Park along the route of the first train into Chattanooga - the Western and Atlantic.
The date 1907 is stamped into several of the concrete overpasses.
The tunnel's entrance and exit are in such remote locations on the mountainside that most residents never see them.