A
- A. E. Staley (Decatur, Illinois)
- Alton Steel (Alton, Illinois)
- American River Transportation Company (Decatur, Illinois)
- Archer Daniels Midland (Decatur, Illinois)
- ArmaLite (Geneseo, Illinois)
- Aventine Renewable Energy (Pekin, Illinois)
- Axium Foods (South Beloit, Illinois)
Read more about this topic: List Of Illinois Companies