| YAN | Yancey R.R. Co. | 1/75; added 1/80; 1/80; eliminated 10/89 |
| YARR | Youngstown & Austintown R.R., Inc. | added 4/85 |
| Ohio R.R. System | eliminated 10/92 | |
| Columbus & Ohio River R.R. Co., Inc. | added 10/92 | |
| Youngstown & Austintown R.R., Inc. | 1/94-7/2000 | |
| YB | The Youngstown Belt R.R. Co. | added 4/97; 7/2000 |
| YDCX | Yankeetown Dock Corp. | added 7/79; 1/80; eliminated 1/80 |
| YEMX | Yesera Monterrey, S.A. | 10/57; eliminated 1/58 |
| YKR | Yorkrail, Inc. | added 10/89; 1/94; eliminated 4/2000 |
| York Ry. Co. | added 4/2000; 7/2000 | |
| YN | Youngstown and Northern R.R. Co. | 1/75-1/80; eliminated 1/81; eliminated 7/81 |
| YOKX | Yale Oil Association | Apr-38 |
| YOTX | Yale Oil Tank Line Co. | Apr-38 |
| YRC | York Ry. Co. | added 4/2000; 7/2000 |
| YS | Youngstown & Suburban Ry. Co. | 4/38-1/52; 10/57-4/70 |
| Youngstown & Southern Ry. Co. | 1/75-1/80; eliminated 7/93; 1/94-7/2000 | |
| YSDX | The Youngstown Steel Door Co. | 1/80; eliminated 1/83 |
| YSLR | Yolo Shortline R.R. Co. | added 4/91; eliminated 7/91; 1/94-7/2000 |
| YSMX | Panama Gypsum Co. | added 1/62; 7/65-1/75; eliminated 4/76 |
| Canadian Gypsum Co., Ltd. | added 4/76; 1/80; eliminated 4/91 | |
| YSTX | The Youngstown Sheet & Tube Co. | 4/38-1/80 |
| YVRR | Yadkin Valley R.R. Co. | added 7/90; eliminated 7/93; 1/94; added 1/96; 7/2000 |
| YVT | Yakima Valley Transportation Co. | 1/75-1/80; eliminated 1/86; 7/2000 |
| YW | Yreka Western R.R. Co. | 1/75-7/2000 |