The high point of the spectacular, 80 mile section of US 550 through the San Juan Mountains is 11,018 foot Red Mountain Pass, named after the colorful, mineralized peaks that rise above the east side of the highway. There are three distinct summits of Red Mountain, closest being 12,894 foot Number 3; Number 2 lies nearly mile north, and Number 1 two miles east. The red color is due to oxidized iron ore, though it was the associated silver, found in lengthy pipes, that was the target of mining activities here - mostly between 1882 and 1893, followed by sporadic excavations until the 1970s. Smaller amounts of copper, gold, lead and zinc were also obtained.

The Red Mountain Mining District extends for over five miles, from the pass northwards to Ironton Park, a marshy, flat-floored valley 1,500 feet lower; at its peak the whole area included nearly 40 mines and six small towns; Albany, Congress, Chattanooga, Guston, Ironton and Red Mountain (the most populous), though little remains of any of these. Some of the district is privately owned and not open to the public - in part due to dangerous structures and open shafts, and partly due to ongoing clean-up operations involving tailings ponds and streams - while other areas need a 4WD vehicle to explore.


Much can be seen from the roadside, however, and there is one accessible area near the pass, beside Idorado Mine, the most recently-closed. The main accessible relics here are a large wooden trestle, a tunnel entrance, and a group of wooden houses, all empty and partly ruinous, scenically situated between colorful, wooded slopes.