M
| Railway name | Locale | Operating years | Comments |
|---|---|---|---|
| Maine Central Railroad | southwestern New Brunswick | Sold and renamed GRS/ST. | |
| Manitoba Great Northern Railway | Subsidiary of GN. | ||
| Manitoba and North Western Railway | Acquired by CPR. | ||
| Maritime Coal Railway and Power Company | northwestern Nova Scotia | 1906–1961 | Abandoned. |
| Metropolitan Electric Railway | |||
| Michigan Central Railroad | Operated in Canada as CASO. | ||
| Midland Railway of Canada | Acquired by GTR. | ||
| Midland Railway of Manitoba | Subsidiary of GN. | ||
| Millertown Railway | Subsidiary of AND. Abandoned. | ||
| Montreal and Champlain Railroad | 1857–1872 | Acquired by GTR. | |
| Montreal and Ottawa Railway | Acquired by CPR. CP operates to Rigaud, line from Rigaud to Ottawa abandoned and sold to VIA Rail. | ||
| Montreal and Vermont Junction Railway | Acquired by CNR. | ||
| Montreal Tramways Company | |||
| Montreal Suburban Tramway and Power | Owned Dominion Park | ||
| Morrissey Fernie and Michel Railway | Subsidiary of CPCC. |
Read more about this topic: List Of Defunct Canadian Railways