I came across these 1920's postcards of the "Phantom Canon Highway" as the grade of the Florence & Cripple Creek was then (and still) known. In its early incarnation, the highway was directly on the grade and used all of the railroad bridges and trestles (all of which were painted white according to the description on the back of one of the cards). Seems as though it was still marketed as a tourist attraction and many of the card locations had also been used for postcards when the railroad was still functioning.
I will post the backs of the cards (kind of interesting to read the descriptions)
Jason Midyette