Entrance to the Carlton tunnel in 1932, in the snow.
The Busk-Ivanhoe Tunnel was built by the Busk Tunnel Railway Company for the Colorado Midland Railroad in 1891 as a replacement for the Hagerman Tunnel at a lower, more direct route. It connected Aspen and Leadville.
The tunnel was abandoned following Colorado Midland's 1897 bankruptcy and was converted to one-way auto traffic in 1922 as the Carlton Tunnel, a toll tunnel carrying then-State Highway 104. After a tunnel collapse, the tunnel was closed in 1943.
Since 1962, the tunnel has been used as part of the Fryingpan-Arkansas Project to carry water across the Continental Divide, moving water between Ivanhoe Lake and Busk Creek.
Correction added July 2016: The tunnel was not part of the Frying Pan-Arkansas project. The Carlton family sold their interest to Rocky Ford Canal Company, who later sold to Pueblo Water Company half of the water rights (1971) and in 1988, the other half to the City of Aurora.
