M
- Macdonald Hotel, Edmonton
- Maganetawan River Railway
- Mackenzie Mann and Company
- Malone and St. Lawrence Railway
- Manitoba Northern Railway
- Manitoba Railway
- Manitoba and South Eastern Railway
- Market Gardens
- Marmora Iron Company
- Marmora Railway and Mining Company
- Massena Springs and Fort Covington Railroad
- Maskinonge and Nipissing Railway
- Medonte Tramway Company
- Michigan Air Line Railway
- Michigan Railway
- Middleton and Victoria Beach Railway
- Midland Extension Railway
- Midland Railway of Canada
- Midland Superior Express
- Minnesota and Manitoba Railroad
- Minnesota and Ontario Bridge Company
- Missisquoi Junction Railway
- Missisquoi Railroad
- Missisquoi Valley Railroad
- Moncton and Buctouche Railway
- Moncton and Northumberland Strait Railway
- Montalta Holdings
- Montfort Colonization Railway
- Montfort and Gatineau Colonization Railway
- Montpelier and White River Railroad
- Montreal and Bytown Railway
- Montreal and Champlain Junction Railway
- Montreal and Champlain Railroad
- Montreal and City of Ottawa Junction Railway
- Montreal and European Short Line Railway
- Montreal and Bytown Railway
- Montreal, Chambly and Sorel Railway
- Montreal and Champlain Junction Railway
- Montreal and Champlain Railroad
- Montreal and City of Ottawa Junction Railway
- Montreal and European Short Line Railway
- Montreal Fruit and Produce Terminal Company
- Montreal Island Belt Line Railway
- Montreal and Kingston Railroad
- Montreal and Kingston Railway
- Montreal and Lachine Railroad
- Montreal and New York Railroad
- Montreal, Portland and Boston Railway
- Montreal and Province Line Junction Railway
- Montreal and Province Line Railway
- Montreal Railway Terminus Company
- Montreal and Sorel Railway
- Montreal and Southern Counties Railway
- Montreal Stock Yards Company
- Montreal Telegraph Company
- Montreal Terminal Railway
- Montreal and Vermont Junction Railway
- Montreal Warehousing Company
- Morden and North-Western Railway
- Mountain Park Coals
- Mountain Park Coal Syndicate
- Mount Royal Tunnel and Terminal Company
- Muskegon Railway and Navigation Company
- Musquodoboit Railway
Read more about this topic: List Of Canadian National Railways Companies