A
- Acadia Coal Company
- Addison Railroad
- Alberta and Great Waterways Railway
- Alberta Midland Railway
- Albert Railway
- Alexander Gibson Railway and Manufacturing Company
- American Union Telegraph Company
- Amherst and Belchertown Railroad
- Amherst, Belchertown and Palmer Railroad
- Anglo-American Telegraph Company
- Annapolis and Atlantic Railway
- Atlantic and Lake Superior Railway
- Atlantic and St. Lawrence Railroad
- Atlantic, Quebec and Western Railway
- Autoport Limited
- Aqua Train
Read more about this topic: List Of Canadian National Railways Companies