The Alpine Tunnel was a narrow-gauge railroad bore under the Continental Divide

Above St. Elmo, the railroad did something hard to imagine now: it tunneled straight through the Continental Divide.

In the early 1880s the Denver, South Park and Pacific Railroad drove the Alpine Tunnel under the Divide to reach mining country on the other side. It was a narrow-gauge line, built for steep, tight mountain railroading, and the bore was a costly, dangerous piece of engineering at high elevation. The tunnel opened a trade route west, carried traffic for a few decades, and was abandoned around 1910 as mining faded and better routes won out.

What remains is the Alpine Tunnel Historic District: the old railbed, stone structures, and the tunnel approaches, with the route reaching up into Chaffee County above St. Elmo. It sits on national forest land and is managed as a historic site, so the grade now serves hikers and high-clearance travelers instead of trains.

For a new resident, this is a window into how completely railroads once shaped these mountains, and how quickly that world ended. The work was enormous, and the line still closed when the mines did.

The structures are old and fragile and the elevation is serious, so plan carefully. For the documented history, see History Colorado and the Colorado Encyclopedia’s pages on the Alpine Tunnel Historic District.