ARZC
| Arizona and California Railroad | 1 |
ATSF
| Atchison Topeka & Santa Fe | 34 |
BC
| BARRE & CHELSEA RAILROAD | 1 |
BN
| Burlington Northern | 7 |
BNSF
| BNSF Railway | 19 |
CN
| Canadian National Railways | 2 |
CNW
| Chicago & Northwestern | 1 |
DRGW
| Denver & Rio Grande Western | 4 |
DRGX
| Denver and Royal Gorge Railway LLC | 3 |
FXE
| Ferromex | 1 |
GREX
| Georgetown Rail Equipment Company | 2 |
KCCX
| Kennecott Utah Copper Corporation | 2 |
LMIX
| Loram Maintenance of Way Inc. | 1 |
MP
| Missouri Pacific | 7 |
MPX
| COLUMBIAN CARBON CO., MAGNETIC PIGMENT DIV. | 1 |
NN
| Northern Nevada Railroad Corporation | 4 |
NWP
| Northwestern Pacific Railroad Company | 1 |
RGAX
| RGAX | 15 |
SLRG
| San Luis and Rio Grande Railroad | 1 |
SP
| Southern Pacific | 2 |
SPMW
| Southern Pacific Maintenance of Way | 44 |
SRS
| Sperry Rail Service | 1 |
SSW
| St Louis Southwestern (Cotton Belt) | 3 |
UP
| Union Pacific Railroad Company | 37 |
UPMW
| UPMW | 1 |
UPP
| Union Pacific Passenger | 1 |
UPX
| UPX | 1 |