IMHO one of the best loops in Colorado: Durango to Ridgway to Telluride to Dolores to Durango. This is marked as the San Juan Scenic Byway on road signs. Awesome!
US Hwy 550 is known as The Million Dollar Highway. Carved into steep cliffs in 1930 for a cost of over a million dollars a mile. It has very few guardrails so the snowplows can push the snow over the 500' drop offs.
Coal Bank Pass - 10,640 ft. 3240 m.
Molas Pass - 10,970 ft., 3,340 m.
Red Mountain Pass - 11,018 ft., 3,358 m.
One of The best roads in Colorado.
A route well worth taking. Especially between Silverton and Ouray; this section is exceptional in both road and scenery. spectacular.