 Rio Grande Southern Railroad connected to San Juan Extension in Durango and went though western edge of San Juan Mountains to Ridgway, Colorado on Montrose–Ouray branch.The D&RG built west from Leadville over Tennessee Pass in an attempt to reach the mining areas around Aspen, Colorado before its rival railroad in the area, the Colorado Midland, could build a line reaching there.The D&RG built a line through Glenwood Canyon to Glenwood Springs, reaching Aspen in October 1887.