| Abbreviation | Definition |
|---|---|
| SLAL | South Plains Lamesa Railroad |
| SLAW | St. Lawrence Railroad |
| SLAX | St. Lawrence Starch |
| SLBU | Showa Line Limited |
| SLC | San Luis Central Railroad |
| SLC | San Luis Central Railroad Company |
| SLCU | SLC Societe Location Containers |
| SLCU | Societe Location Containers |
| SLDU | Showa Line Limited |
| SLEX | Short Line Enterprises Limited |
| SLFU | Showa Line Limited |
| SLGG | Progress Rail Services Corporation - Sidney and Lowe Railroad |
| SLGG | Sidney and Lowe Railroad |
| SLGW | Salt Lake Garfield and Western Railway Company |
| SLGW | Salt Lake, Garfield and Western Railway |
| SLH | Sugarloaf and Hazelton Railroad |
| SLHU | Showa Line Limited |
| SLIU | Star Lines Equipment |
| SLIU | Star Lines Equipment Incorporated |
| SLIZ | Star Lines Shipping |