| Abbreviation | Definition |
|---|---|
| IM | IM Industry |
| IMAZ | IMC Agrico |
| IMC | International Mining Corporation |
| IMCC | International Minerals Chemical Corporation |
| IMCU | Industrial Maritime Carriers |
| IMCV | Ivorydale & Mill Creek Valley Railway |
| IMCX | International Minerals and Chemical Corporation (IMC Global Operations) |
| IMCX | International Minerals and Chemicals Railroad (IMC Global Operations Incorporated) |
| IMCZ | IMC Industry |
| IMDU | Seateq Corporation |
| IMEX | Indiana and Michigan Electric |
| IMEX | Indiana and Michigan Electric Company |
| IMEZ | Imery's |
| IMFX | General American Transportation Corporation (GATX) |
| IMHZ | Intermodal Hub |
| IMID | Indiana Midland Railway (AAR code suspended) |
| IMMQ | International Methanex Methane Corporation |
| IMMU | Industrias Monfel |
| IMMX | Industrial Minera Mexico |
| IMMX | Industrial Minera Mexico, S. A. |