| Abbreviation | Definition |
|---|---|
| SLIZ | Star Lines Shipping Company Inc |
| SLKU | Sea-Link Container Lines |
| SLOU | Showa Line Limited |
| SLOX | Selox |
| SLQ | St. Lawrence and Atlantic Railroad (Genesee & Wyoming) |
| SLR | St. Lawrence and Atlantic Railroad |
| SLR | St. Lawrence and Atlantic Railroad (Genesee & Wyoming) |
| SLR | The Strawberry Light Railway |
| SLRG | San Luis and Rio Grande Railroad |
| SLRR | St. Lawrence and Raquette River Railroad |
| SLRS | SMS Rail Service |
| SLRS | SMS Rail Service Incorporated |
| SLRT | Southwest Light Rail Transitway |
| SLRU | Showa Line Limited |
| SLRX | St. Louis Refrigerator Car |
| SLSF | Burlington Northern and Santa Fe Railway Company |
| SLSF | St. LouisSan Francisco Railway (BNSF Railway) |
| SLSF | St. Louis–San Francisco Railway (BNSF Railway) |
| SLSU | Spinnaker Leasing Corporation |
| SLTX | Slade Transport |