| Name | Mark | System[1] | From | To | Successor | Notes |
|---|
| Big Blackfoot Railway | | MILW | 1910 | 1916 | Chicago, Milwaukee and St. Paul Railway |
| Big Horn Railroad | | CB&Q | 1905 | 1916 | Chicago, Burlington and Quincy Railroad |
| Big Horn Southern Railroad | | CB&Q | 1888 | 1897 | Chicago, Burlington and Quincy Railroad |
| Billings and Central Montana Railway | | NP | 1912 | 1921 | Northern Pacific Railway |
| Billings and Northern Railroad | | GN | 1902 | 1907 | Great Northern Railway |
| Bozeman Street Railway | | MILW | 1892 | 1909 | Gallatin Valley Electric Railway |
| Burlington Northern Inc. | BN | | 1970 | 1981 | Burlington Northern Railroad |
| Burlington Northern Railroad | BN | | 1981 | 1996 | Burlington Northern and Santa Fe Railway |
| Butte, Anaconda and Pacific Railway | BA&P, BAP | | 1892 | 1985 | Rarus Railway |
| Butte, Wisdom and Pacific Railway | | | 1913 | 1914 | Southern Montana Railway |
| Camp Creek Railway | | NP | 1911 | 1914 | Northern Pacific Railway |
| Chicago, Burlington and Quincy Railroad | CB&Q | CB&Q | 1894 | 1970 | Burlington Northern Inc. |
| Chicago, Burlington and Quincy Railway | | CB&Q | 1901 | 1907 | N/A | Leased the Chicago, Burlington and Quincy Railroad |
| Chicago, Milwaukee and Puget Sound Railway | | MILW | 1909 | 1912 | Chicago, Milwaukee and St. Paul Railway |
| Chicago, Milwaukee and St. Paul Railway | | MILW | 1912 | 1928 | Chicago, Milwaukee, St. Paul and Pacific Railroad |
| Chicago, Milwaukee and St. Paul Railway of Montana | | MILW | 1905 | 1908 | Chicago, Milwaukee and St. Paul Railway of Washington |
| Chicago, Milwaukee and St. Paul Railway of Washington | | MILW | 1908 | 1909 | Chicago, Milwaukee and Puget Sound Railway |
| Chicago, Milwaukee, St. Paul and Pacific Railroad | MILW | MILW | 1928 | 1982 | Burlington Northern Railroad |
| Clearwater Short Line Railway | | NP | 1898 | 1914 | Northern Pacific Railway |
| Coeur d'Alene Railway and Navigation Company | | NP | 1886 | 1897 | Northern Pacific Railway |
| Drummond and Philipsburg Railroad | | NP | 1887 | 1888 | Northern Pacific and Montana Railroad |
| Elliston and Southern Railroad | | | 1896 | | N/A |
| Gallatin Valley Railway | | MILW | 1910 | 1918 | Chicago, Milwaukee and St. Paul Railway |
| Gallatin Valley Electric Railway | | MILW | 1908 | 1910 | Gallatin Valley Railway |
| Gaylord and Ruby Valley Railway | | NP | 1897 | 1899 | Northern Pacific Railway |
| Gilmore and Pittsburgh Railroad | | NP | 1907 | 1939 | N/A |
| Great Falls and Canada Railway | | GN | 1889 | 1901 | Montana and Great Northern Railway |
| Great Falls Terminal Railway | | MILW | 1912 | 1914 | Chicago, Milwaukee and St. Paul Railway |
| Great Falls and Teton County Railway | | GN | 1912 | 1914 | Great Northern Railway |
| Great Northern Railway | GN | GN | 1890 | 1970 | Burlington Northern Inc. |
| Helena, Boulder Valley and Butte Railroad | | NP | 1886 | 1888 | Northern Pacific and Montana Railroad |
| Helena and Jefferson County Railroad | | NP | 1883 | 1898 | Northern Pacific Railway |
| Helena and Northern Railroad | | NP | 1886 | 1888 | Northern Pacific and Montana Railroad |
| Helena and Red Mountain Railroad | | NP | 1886 | 1899 | Northern Pacific Railway |
| Minneapolis, St. Paul and Sault Ste. Marie Railroad | SOO | CP | 1944 | 1961 | Soo Line Railroad |
| Minneapolis, St. Paul and Sault Ste. Marie Railway | SOO | CP | 1913 | 1944 | Minneapolis, St. Paul and Sault Ste. Marie Railroad |
| Missoula and Bitter Root Valley Railroad | | NP | 1887 | 1888 | Northern Pacific and Montana Railroad |
| Missoula and Hamilton Railway | | NP | 1911 | 1916 | Northern Pacific Railway |
| Missouri River Railway | | NP | 1906 | 1914 | Northern Pacific Railway |
| Montana Railroad | | MILW | 1894 | 1910 | Chicago, Milwaukee and Puget Sound Railway |
| Montana Railway | | NP | 1881 | 1898 | Northern Pacific Railway |
| Montana Central Railway | | GN | 1886 | 1907 | Great Northern Railway |
| Montana Eastern Railway | | GN | 1912 | 1928 | Great Northern Railway |
| Montana and Great Northern Railway | | GN | 1901 | 1907 | Great Northern Railway, St. Paul, Minneapolis and Manitoba Railway |
| Montana Southern Railway | | | 1917 | 1940 | N/A |
| Montana Southern Railway | | NP | 1893 | 1897 | Gaylord and Ruby Valley Railway |
| Montana Union Railway | | NP | 1886 | 1898 | Northern Pacific Railway |
| Montana Western Railway | MWRR | | 1986 | 2003 | Burlington Northern and Santa Fe Railway |
| Montana Western Railway | | | 1909 | 1970 | Burlington Northern Inc. |
| Montana, Wyoming and Southern Railroad | MW&S, MWS | | 1909 | 1955 | N/A |
| Northern Pacific Railroad | | NP | 1864 | 1896 | Northern Pacific Railway |
| Northern Pacific Railway | NP | NP | 1896 | 1970 | Burlington Northern Inc. |
| Northern Pacific and Montana Railroad | | NP | 1888 | 1898 | Northern Pacific Railway |
| Oregon Short Line Railroad | | UP | 1897 | 1987 | Union Pacific Railroad |
| Oregon Short Line and Utah Northern Railway | | UP | 1889 | 1897 | Oregon Short Line Railroad |
| Rarus Railway | RARW | | 1985 | 2007 | Butte, Anaconda and Pacific Railway |
| Rocky Fork and Cooke City Railway | | NP | 1886 | 1898 | Northern Pacific Railway |
| Rocky Mountain Railroad of Montana | | NP | 1881 | 1898 | Northern Pacific Railway |
| St. Paul, Minneapolis and Manitoba Railway | | GN | 1879 | 1907 | Great Northern Railway |
| Shields River Valley Railway | | NP | 1908 | 1914 | Northern Pacific Railway |
| Soo Line Railroad | SOO | CP | 1961 | | | Still exists in Montana as a lessor of the Dakota, Missouri Valley and Western Railroad |
| Southern Montana Railway | | | 1914 | 1917 | Montana Southern Railway |
| Utah and Northern Railway | | UP | 1878 | 1889 | Oregon Short Line and Utah Northern Railway |
| White Sulphur Springs and Yellowstone Park Railway | WSYP | MILW | 1910 | 1980 | N/A |
| Yellowstone Park Railroad | | | 1905 | 1909 | Montana, Wyoming and Southern Railroad | |
