Colorado Joint Line
Legend
Moffat Tunnel Subdivision Brush Subdivision Denver Union Station Ball Arena–Elitch Gardens RTD light rail Kountry Line 10th & Osage Alameda I-25 & Broadway Evans Englewood Oxford–City of Sheridan Littleton–Downtown Littleton–Mineral Big Lift Terminal Palmer Lake elev. 7,237 ft (2,206 m) Colorado Springs US Army Railroad Nixon Power Plant UP Tennessee Pass Subdivision Pueblo Yard Pueblo Union Depot BNSF Pueblo Subdivision BNSF Spanish Peaks Subdivision
Union Pacific Colorado Springs Subdivision BNSF Pikes Peak Subdivision other lines

The Colorado Joint Line is a railway corridor in Colorado running north-south between Denver and Pueblo. Presently the tracks are owned by the BNSF Railway and the Union Pacific Railroad and operated jointly.

The first set of tracks in the area were laid by the Denver and Rio Grande Railroad in 1871. The Atchison, Topeka and Santa Fe Railway laid their tracks parallel to the D&RG in 1888. In 1900 the Colorado and Southern negotiated a trackage rights agreement to run its trains over the AT&SF line. In 1918 during the First World War the United States Railroad Administration dictated that the parallel D&RG and AT&SF lines be operated as a single double-track railroad, with the eastern track carrying all northbound trains, and the western track carrying all southbound traffic. That efficient arrangement continued after the end of the War and right up to the present day.

The line consists of the paired right of ways of the two companies, with ownership being non-continuous since the lines originally crossed over each other three times between Denver and Pueblo at Sedalia, Spruce, and Crews. These cross-overs were later eliminated, creating continuous northbound and southbound tracks. In 1974 the segment between Palmer Lake and Crews was converted to bi-directional single track.^[1]

The Union Pacific, which acquired the D&RGW in 1996, designates the Joint Line as their Colorado Springs Subdivision. The BNSF, which merged the AT&SF and the Burlington Northern in 1996, designates the route as their Pikes Peak Subdivision.^[2] Common traffic over the line largely consists of unit coal trains originating from the Powder River Basin in southeast Montana and northeast Wyoming, however manifest trains are very common as well, and intermodal traffic is not unheard of. Passenger service over the line ended in 1971,^{[citation needed]} making it a freight only route.