Cumbres Pass, Rail mountain pass in San Juan Mountains, Colorado, US

Cumbres Pass is a mountain pass in the San Juan Mountains of Colorado at 10,022 ft (3,055 m), crossed by State Highway 17 and the Cumbres and Toltec Scenic Railroad. The highway climbs at 5.8% from the north and at a gentler 4% from the south.

The Denver & Rio Grande Railroad built the line through the pass in the 1880s as part of their San Juan Extension running from Alamosa to Durango. This route opened access to mining camps and remote settlements across challenging mountain terrain.

The original section house, car inspectors' house and part of the old snowshed still stand at the pass, maintained by the Friends of the Cumbres and Toltec Scenic Railroad. Railroad personnel once lived at the summit full-time when the line operated as a common carrier; today no one lives there.

The pass remains open most of the year, though winter weather can make conditions unpredictable at this elevation. The southern approach offers a gentler grade and is often a better route during seasonal storms.

The facilities at the pass were built by the railroad to turn helper locomotives for their return to Chama and to water engines after the climb. Some structures, including the station building, were demolished when the highway was realigned; the original section house, car inspectors house and part of the old snowshed remain, maintained by the Friends of the Cumbres and Toltec Scenic Railroad.