| Yadkin Valley R.R. Co. | YVRR | added 7/90; eliminated 7/93; 1/94; added 1/96; 7/2000 | |
| Yakima Interurban Lines Assn. | NPRX | Jul-00 | |
| Yakima Valley Transportation Co. | YVT | 1/75-1/80; eliminated 1/86; 7/2000 | |
| Yale Oil Association | YOKX | Apr-38 | |
| Yale Oil Tank Line Co. | YOTX | Apr-38 | |
| Yancey R.R. Co. | YAN | 1/75; added 1/80; 1/80; eliminated 10/89 | |
| Yankeetown Dock Corp. | YDCX | added 7/79; 1/80; eliminated 1/80 | |
| Yesera Monterrey, S.A. | YEMX | 10/57; eliminated 1/58 | |
| Yolo Shortline R.R. Co. | YSLR | added 4/91; eliminated 7/91; 1/94-7/2000 | |
| York Ry. Co. | YKR | added 4/2000; 7/2000 | |
| YRC | added 4/2000; 7/2000 | ||
| MPA | added 4/2000; 7/2000 | ||
| Yorkrail, Inc. | YKR | added 10/89; 1/94; eliminated 4/2000 | |
| Young Refining Corp. | CACX | eliminated 10/72 | |
| Youngstown & Austintown R.R., Inc. | YARR | added 4/85 | |
| YARR | 1/94-7/2000 | ||
| Youngstown & Southern Ry. Co. | YS | 1/75-1/80; eliminated 7/93; 1/94-7/2000 | |
| MTR | 1/94-7/2000 | ||
| PLE | added 4/93; eliminated 10/93; 1/94-7/2000 | ||
| Youngstown & Suburban Ry. Co. | YS | 4/38-1/52; 10/57-4/70 | |
| Youngstown and Northern R.R. Co. | YN | 1/75-1/80; eliminated 1/81; eliminated 7/81 | |
| Yreka Western R.R. Co. | YW | 1/75-7/2000 | |