C W McCall, "Wolf Creek Pass". We drove over the pass in the late 60s, no tunnel. My father lived in the area in the 40s, no tunnel. In the mid 70s we came from Chama up through Pagosa Springs, and on to Durango, missing the pass. Stopping in Pagosa Springs, at the general store, we saw a postcard of "The Tunnel", labeled as such, clearly showing a fairly new snowshed.
From the Wikipedia entry for "Wolf Creek Pass":
"The song describes the truck careening down through a "tunnel" (during which process several crates of chickens stacked on the back of the truck are inadvertently lost) and eventually into a feed store in Pagosa Springs. This tunnel is actually a snow shed: the song predates the only true tunnel on the pass by 30 years. However, the snow shed is on the east side of the pass while Pagosa Springs is on the west side, making this sequence of events impossible."
Also, it appears there is now a true tunnel on the pass, as well as many other improvements:
"A 900-foot (270 m) tunnel on the eastern portion was opened November 5, 2005. Construction was completed in the Summer of 2006, with the highway fully widened and drainage projects along the route completed."
Incidentally, the song claims the clearance is 12 feet, but the highway is a major truck route, so that seems very unlikely. I doubt that a trucker would "lose the top row of chickens" going through it.
