| Abbreviation | Definition |
|---|---|
| SSCU | States Steamship Company |
| SSCZ | States Steamship |
| SSCZ | States Steamship Company |
| SSD | Union Pacific Railroad |
| SSD | Union Pacific Railroad Company |
| SSDK | Savannah State Docks Railroad |
| SSDK | Savannah State Docks Railroad Company |
| SSGX | McMaster Grain |
| SSH | South Shore |
| SSH | South Shore Railroad |
| SSIU | Japan Line Limited |
| SSIX | General Electric Railcar Services Corporation |
| SSIX | Itel Corporation |
| SSIZ | Japan Line Limited |
| SSJR | Sheffield Station Junction Railway |
| SSJU | Sumitomo 3M |
| SSLV | Southern San Luis Valley Railroad |
| SSLZ | Sea Star Line |
| SSMX | David J. Joseph Company |
| SSMX | Joseph Transportation |