| Abbreviation | Definition |
|---|---|
| ADMX | Archer Daniels Midland |
| ADN | Arkansas Louisiana and Mississippi Railroad Company |
| ADN | Ashley, Drew and Northern Railway (Arkansas, Louisiana and Mississippi Railroad) |
| ADRX | Addeleston Recycling Corporation |
| ADSX | Andrew Merrilees |
| ADSX | Andrew Merrilees Limited |
| ADXU | Applied Cryo Technologies |
| AE | Arizona Eastern Railroad |
| AEC | Atlantic and East Carolina Railway |
| AEC | Atlantic and East Carolina Railway Company |
| AECX | Associated Electric Cooperative |
| AECX | Associated Electric Cooperative Incorporated |
| AEEU | Alion Energy |
| AEFR | Aurora Elgin and Fox River Electric |
| AEFR | Aurora, Elgin and Fox River Electric |
| AEIX | Alan Eslisk |
| AEIZ | Farrell Lines |
| AEIZ | Farrell Lines Incorporated |
| AEPU | American Lines |
| AEPU | American Lines Incorporated |