I've been looking at maps today and wonder why the D&RG surveyors did not place the route of the San Jaun Extension in the canyon of the Rio de Los Pinos from Antonito to the river crossing a few miles below Cumbres Pass.
The route would have significantly shorter. Are there steep rapids or falls in the canyon that would make a route along the river side impossible? On google make there are areas of Toltec Gorge that I can's see due to shadows. The rest of the riverside looks like the route could have followed the river.