From KC Junction (MP 144.8), the junction with the north-northwest to south-southeast double track, CTC, CP transcontinental main line at Golden, the single track, OCS line turns away at a wye on the west side, alongside the Columbia River, turning curvily south-southeast to follow the east bank of that river past Golden Yard (MP 143.0), Purcell (MP 140.7), Nicholson (MP 137.0), and the 8,375 ft. siding at Horse Creek (MP 134.0), where it turns curvily southeast up the valley of the Columbia River, which flows north for a few hundred miles before turning west and then south.
The line passes McMurdo (1st), McMurdo (MP 127.4), a detector at MP 123.3, Parson (MP 119.6), the 8,532 ft. siding at Seeney (MP 117.7), Castledale (MP 114.0), Harrogate (MP 109.1), the 8,250 ft. siding at Spillmacheen (MP 102.2), a detector at MP 97.2, Brisco (1st), Brisco (MP 94.3), the 8,374 ft. siding at Luxor (MP 88.3), the 2,085 ft. siding at Edgewater (MP 83.0), Radium (MP 77.6), a detector at MP 74.7. Firlands (MP 73.0), a bridge across the Columbia River to its west bank, and the 6,928 ft. siding at Windermere (MP 68.8), then along the west bank of Lake Windermere, past Goldie Creek (MP 64.4), Goldie Creek (1st), Lake Bank, Rushmere (MP 60.0), Rushmere (1st) and Strata.
Leaving the lake behind, the line turns south-southeast, still following the west bank of the river, past the 9,481 ft. siding at Fairmont (MP 53.7), and Environ (MP 50.4), where there is a detector, and curvily south along the west bank of Columbia Lake, past Columbia Lake (MP 44.9), the headwaters of the Columbia, leaving the lake for Canaflat and the 8,364 ft. siding at Canal Flats (MP38.5), where there is a wye on the east side with a spur to Cranbrook Forest Industries, and the running along the west bank of the upper reaches of the Kootenai River (flowing south, to pass into the USA before returning north to Kootenai Lake), past Copper Creek (MP 34.0), Copper Creek (1st), the 8,775 ft. siding at Torrent (MP 28.1), a detector at MP 25.2, the 2,200 ft. siding at Skookumchuck (MP 22.3), where the river is further east for a few miles, Teepee (MP 17.0), a bridge over the river as it returns, the 8,517 ft. siding at Wasa (MP 12.1), a detector at MP 8.5, and Doyle (MP 6.0) to Fort Steele (MP 0.0), where there is a wye with the Cranbrook subdivision coming in from the west-southwest (across the river), and the Cranbrook subdivision turns south.