The company's main line was narrow gauge and went from Union Station in Denver up the valley of the South Platte River to the town of South Platte, then followed the North Fork of the South Platte through Buffalo Creek and Bailey. West of Bailey the route along North Fork and through the north end of the Tarryall Mountains essentially followed the route of present-day U.S. Highway 285 to Como, where it branched northward (see below). From Como the main line traversed South Park to Garo, where a spur went northward to Fairplay and Alma. The main line continued south over Trout Creek Pass. On the western side of the pass, a small spur of the main connected to Buena Vista, then traversed the southern end of the Sawatch Range through the Alpine Tunnel to Pitkin and Gunnison. The distance along the main line from Denver to Gunnison was approximately .