On Selasa, 23 April 2013
| QC | = | Quebec Central Railway |
| QCCX | = | Quantum Chemical Corporation |
| QCM | = | Cartier Railway |
| QGRY | = | Quebec Gatineau Railway |
| QNSL | = | Quebec North Shore and Labrador Railway |
| QOCX | = | GE Rail Services |
| QOHX | = | Quaker Oats Company |
| QOTX | = | Quaker Oats Company (Chemicals Division) |
| QRR | = | Quincy Railroad |
| QSMX | = | Quaker State Oil Refining Corporation |
| QSOX | = | Quaker State Oil Refining Corporation |
| QTTX | = | TTX Corporation |
Note: Marks ending in U are for container owners; marks ending in X are not common carriers; marks ending in Z are for trailers without flanged wheels. All other marks are of common-carrier railroads.
