| Abbreviation | Definition |
|---|---|
| ATTX | TTX Company |
| ATW | Atlantic and Western Railway |
| AUAR | Austin Area Terminal Railroad |
| AUBX | US Plastic Lumber |
| AUBX | US Plastic Lumber, LTD. |
| AUG | Augusta Railroad |
| AUG | Augusta Railroad Corporation |
| AUNW | Austin and Northwestern Railroad |
| AUS | Augusta and Summerville Railroad |
| AUS | Augusta Southern Railroad |
| AVCU | Amvac Chemical Coporation |
| AVCX | AVCO Aerostructures Division |
| AVE | Alta Velocidad Española |
| AVL | Aroostook Valley Railroad |
| AVL | Aroostook Valley Railroad Company |
| AVLU | Allied Van Lines |
| AVR | Allegheny Valley Railroad |
| AVR | Allegheny Valley Railroad Company |
| AVSU | REC Advanced Silicon Materials |
| AW | Ahnapee and Western Railway |