The following rail lines have been owned or operated by the Denver and Rio Grande Western Railroad or its predecessors.
- Fort Logan Branch: Englewood (Military Junction) to Fort Logan
- Lehigh Branch: Louviers (Lehigh Junction) to Lehigh Mine
- Castle Rock Branch: Castle Rock to Hathaway
- Douglas Quarry Spur: Douglas to Madge Quarry
- Manitou Branch: Colorado Springs (Manitou Junction) to Manitou
- Royal Gorge Line: Pueblo to Salida via Royal Gorge
- Coal Creek Branch: Florence to Coal Creek
- Oak Creek Branch: Florence (Oak Creek Junction) to Oak Creek
- Chandler Creek Branch: Chandler Junction to Chandler Mine
- Grape Creek Branch: Cañon City (Grape Creek Junction) to Westcliffe
- Westcliffe Branch: Texas Creek to Westcliffe
- Howard Branch: Howard's Quarry Junction to Calcite
- Calumet Branch: Brown Canon (Hecla Junction) to Calumet
- Leadville Branch: Malta to Leadville
- Ryan Cut-Off: Leadville Junction to Leadville (Leadville Branch)
- Aspen Branch: Glenwood Springs to Aspen
- Gunnison Line: Salida to Grand Junction via Marshall Pass and Black Canyon
- Monarch Branch: Poncha Junction to Monarch
- Mears Junction-Alamosa Line: Mears Junction to Alamosa
- Pitkin Branch: Parlin to Quartz
- Crested Butte Branch: Gunnison to Anthracite
- Baldwin Branch: Gunnison to Baldwin
- Aberdeen Branch: Gunnison (Aberdeen Junction) to Aberdeen Quarry
- Lake City Branch: Sapinero to Lake City
- Ouray Branch: Montrose to Ouray
- North Fork Branch: Delta (North Fork Junction) to Oliver
- Ballard and Thompson Railroad: Thompson to Sego
- Cane Creek Branch: Brendel to Potash
- Sunnyside Branch: Mounds to Sunnyside
- Spring Canyon Branch: Helper (Spring Canyon Junction) to Mutual
- Kenilworth Branch: Helper (Kenilworth Junction) to Kenilworth
- Jennings and Potter's Quarry Branch: Kyune (Jennings Junction) to quarries
- Pleasant Valley Branch: Colton to Clear Creek
- Marysvale Branch: Thistle to Marysvale
- Tintic Branch: Springville to Silver City
- Provo Canyon Branch: Provo to Heber City
- Orem Branch: Provo (Provo Junction) to Orem
- Bingham Branch: Midvale to Bingham
- Little Cottonwood Branch: Midvale to Wasatch
- Park City Branch: Roper Junction to Park City
- Lake Park Branch: Farmington (Lake Park Junction) to Lake Park
- Hooper Branch: Roy to Cox
- Old Main Line: Minnequa (Sonora Junction) to Trinidad; branch from Cuchara Junction to Walsenburg (Walsenburg Junction)
- Rouse Branch: Rouse Junction to Rouse (later began at Mayne and then Monson on the C&S trackage rights)
- Engleville Branch: Engleville Junction to Engleville
- Zinc Smelter Spur: Minnequa (Zinc Junction) to Blende
- Capers Branch: Mustang to Capers (including part of the Old Main Line near Capers)
- Colorado and Southern Railway trackage rights: Walsenburg to Longsdale Junction
- Loma Branch: Walsenburg (Loma Junction) to Alamo
- Reliance Branch: La Veta (Reliance Junction) to Ojo
- Tropic Spur: La Veta (Tropic Junction) to Tropic
- Creede Branch: Alamosa to Creede
- Santa Fe Branch: Antonito to Santa Fe
- Chama Lumber Spur: Chama (Biggs Junction) to Tierra Amarilla
- Pagosa Springs Branch: Gato (Pagosa Junction) to Pagosa Springs
- Rio Grande and Southwestern Railroad: Lumberton to Gallinas
- Farmington Branch: Carbon Junction to Farmington
- Silverton Branch: Durango to Silverton
- Moffat Line: Denver (Union Station) to Dotsero (Tennessee Pass Line) via Moffat Tunnel
- Corona Line: Newcomb to Vasquez (old line over Corona Pass; abandoned when Moffat Tunnel opened)
- Craig Branch: Bond (Orestod) to Craig
- Rio Grande Southern Railroad: Ridgway (Ouray Branch) to Durango