| Qilico Ltd. c/o SC Capital Corp. | QLMX | added 10/94; eliminated 10/97 | |
| QO Chemicals, Inc. | QOTX | added 10/84; 1/94; eliminated 10/95 | |
| PNTX | 1/94; eliminated 10/95 | ||
| Quachita R.R. | OUCH | added 4/91; 1/94-7/2000 | |
| Quaker City Live Stock Express (General American Transportation Corp.) | QLSX | Apr-38 | |
| Quaker City Tank Line (General American Transportation Corp.) | QTX | Apr-38 | |
| Quaker Oats Co. | QOCX | 1/94-7/2000 | |
| QOHX | added 10/80; 1/94-7/2000 | ||
| Quaker Oats Co.-Chemicals Division | QOTX | added 10/80; eliminated 10/84 | |
| Quaker State Corp. | QSMX | added 10/87; 1/94; eliminated 10/94; 7/2000 | |
| Quaker State Oil Refining Corp. | QSMX | 4/38-1/80; eliminated 10/87 | |
| Quality Rail Services, LLC | QUAX | added 1/2000; 7/2000; eliminated 4/2001 | |
| Quality Railway Services & Supply Co. | QRSX | 7/2000; eliminated 7/2001 | |
| Quanah, Acme & Pacific Ry. Co. | QAP | 4/38-1/80; eliminated 7/81 | |
| Quantum Chemical Corp. | QCCX | added 1/97 | |
| Quantum Chemical Corp., USI Division | QCCX | eliminated 4/98 | |
| NPCX | added 7/88; 1/94; eliminated 4/98 | ||
| USIX | added 7/88; 1/94; eliminated 4/98 | ||
| Quantum Chemical Corporation, USI Division | CHEX | added 7/88; 1/94; eliminated 4/98 | |
| Quartermaster Corps, War Department, U.S.A. | GPRX | Apr-38 | |
| USQX | Apr-38 | ||
| Quebec Central Ry. | QC | 4/38-10/57 | |
| Quebec Central Ry. Co. | QC | 1/75-1/94; eliminated 7/94 | |
| Quebec Gatineau Ry., Inc. | QGRY | added 10/98; 7/2000 | |
| Quebec Ry. Corp. Inc. | QRC | Jul-00 | |
| Quebec Ry. Light & Power Co. | QLP | 4/38-4/70 | |
| Quebec Southern Ry. | QSR | added 4/97; 7/2000; eliminated 4/2001 | |
| Quebec, Montreal & Southern Ry. | QMS | 4/38-1/52 | |
| Quest Communications Corp. | SPCH | Jul-00 | |
| Quimica Fluor, S.A. de C.V. | QFFX | added 4/93; 1/94-7/2000 | |
| Quincy Bay Terminal Co. | QBT | added 10/92; 1/94-7/2000 | |
| Quincy R.R. Co. | QRR | 1/75-7/2000 | |
| Qwest Communications Corp. | SPCX | added 4/98; eliminated 7/98; 7/2000 | |