The Denver, South Park & Pacific Railroad followed the Platte River from Denver to Kenosha Pass, crossed South Park, and reached Buena Vista in 1880.  The narrow-gauge railroad then tackled Chalk Creek Canyon and crossed under the Continental Divide in the Alpine Tunnel.  Some sources claim that 10,000 men labored to build the tunnel.  Even being paid three times the typical daily wage, workers could not tolerate the 11,200 altitude, bitter cold and blinding blizzards.  

The South Park Line investors hoped to make their fortune by transporting equipment and supplies to the booming mining towns, and hauling the ore back down.  Instead, the railway suffered from the boom-and-bust cycle of mining ad out in a flood.  Boreas Pass, from the roundhouse in Como to Breckenridge, functioned from 1884-1936 and is now a scenic dirt road.  The Leadville, Colorado & Southern tourist train rides on the DSP&P tracks underwent many owners and name changes.  When the Depot in Buena Vista was built, the South Park Line was part of the Denver, Leadville and Gunnison Railway, which was itself owned by Union Pacific.  Later, it merged into the Colorado and Southern Railway.

The line shut down piecemeal.  In 1910, the Alpine Tunnel was closed by a cave-in and the Trout Creek Pass section, with twenty-seven bridges, washed out in a flood.  Boreas Pass, from the roundhouse in Como to Breckenridge, functioned from 1884-1936 and is now a scenic dirt road.  The Leadville, Colorado & Southern tourist train rides on the DSP&P tracks.