| Railroad Name | Railroad Initials |
| A. E. Staley Manufacturing | AESX |
| ACF Leasing | ACFX |
| Alaska Railroad | ARR |
| Alton RR Co (Chicago & Alton RR Co) | C&A |
| Amador Central | Amador |
| American Refrigerator Transit | ART |
| American Refrigerator Transit Co | MODX |
| AMTRAK | AMTRAK |
| Argentine Central | AC |
| Baltimore & Ohio | B&O |
| Beaver Penrose & Northern | BP&N |
| Bessemer & Lake Erie | B&LE |
| Book Cliff Railroad Company | BC |
| Boston & Maine | B&M |
| Burlington Northern | BN |
| Burlington Refrigerator Express | BREX |
| Burlington Refrigerator Express box | RBBX |
| California Street Cable Railroad Co | CSCableRR |
| Canadian Collieries (Dunsmuir) Ltd | CC(D) |
| Canadian National | CN |
| Canadian Pacific | CPR |
| Central American Railroad | FIdeCA |
| Central of Georgia Railway | CG |
| Cherrelyn horse car line, Englewood, CO | Cherrelyn |
| Chicago & Illinois Midland | C&IM |
| Chicago & North Western | Chi&NW |
| Chicago Burlington & Quincy | CB&Q |
| Chicago Great Western | CGW |
| Chicago Milwaukee St Paul & Pacific | MILW |
| Chicago North Shore & Milwaukee | CNS&M |
| Cia Agricola (Guatemala) | Agricola |
| Cia Minera de Penoles-Avalos (Mexico) | Penoles |
| Colonial Sugar Refining (Fiji) | CSR |
| Colorado & North Western | Colo&NW |
| Colorado & Southern | C&S |
| Colorado Central | CC |
| Colorado Midland | CM |
| Colorado Railroad | ColoRR |
| Colorado Springs & Cripple Creek District | CS&CCD |
| Colorado Yule Marble Electric railway | CYME |
| Conoco | CONX |
| Consolidated Rail Corp | Conrail |
| Continental Carbon Co | WITX |
| Cowlitz Chehalis & Cascade Railway | CC&CRy |
| Crystal River & San Juan Railroad | CR&SJ |
| CSX Transportation Co | CSX |
| Dardanelle & Russellville | D&R |
| Delaware & Hudson | D&H |
| Denver & Intermountain | D&IM |
| Denver & Interurban | D&I |
| Denver & Northwestern | D&NW |
| Denver & Rio Grande | D&RG |
| Denver & Rio Grande Western | D&RGW |
| Denver & Salt Lake | D&SL |
| Denver & Swansea | D&S |
| Denver Boulder & Western | DB&W |
| Denver Leadville & Gunnison | DL&G |
| Denver Northwestern & Pacific | DNW&P |
| Denver South Park & Pacific | DSP&P |
| Denver Tramway | DT |
| Duluth Missabe & Iron Range | DM&IR |
| Duluth South Shore & Atlantic | DSS&A |
| East Broad Top | EBT |
| Edaville RR, Massachusetts | Edaville |
| El Paso & Southwestern | EP&SW |
| Electro-Motive Division | EMD |
| Erie | ERIE |
| Erie-Lackawana | EL |
| Ethyl Corporation | EBAX |
| Ferrocarriles Pacifico | FCP |
| Florence & Cripple Creek | F&CC |
| Ford Motor Co | Ford |
| Fort Collins Minicipal Railway | Fort Collins |
| Fort Smith & Western | FS&W |
| Fort Worth & Denver City Railway Co | FW&D |
| Fruit Growers Express Co | FOBX |
| Fruit Growers Supply Co | FGSCo |
| Galesburg & Great Eastern | G&GE |
| General American Refrigerator Express Co. | GARX |
| General American Transportation Corp | GPFX |
| General Motors Corporation | GMC |
| Georgetown Breckenridge & Leadville | GB&L |
| Gilpin Railroad | GRR |
| Gilpin Tramway | GT |
| Golden City & San Juan (Colorado Railroad Museum) | GC&SJ |
| Grand Trunk | GTR |
| Grand Trunk Western | GTW |
| Grand Valley Electric | GVE |
| Great Northern | GN |
| Great Western Railway (Colorado) | GWR |
| Huntingdon & Broad Top Mountain | H&BTM |
| Illinois Central | IC |
| Intermountain Railway Co (Boise) | IRC |
| Kennecott Copper Corporation | KCC |
| Koppers Co. (creosote) | Koppers |
| Laramie North Park & Western | LNP&W |
| Laramie Valley RR Co | LV |
| Lehigh & New England | L&NE |
| Los Angeles & Salt Lake | LA&SL |
| Louisville & Nashville | L&N |
| Maine Central | MeC |
| Manchester & Onieda | M&O |
| Manitou & Pikes Peak | M&PP |
| Midland Terminal | MT |
| mining | mining |
| Minneapolis Northfield & Southern | MNS |
| Minneapolis St Paul & Sault Ste Marie RR | SOO |
| Missouri & Arkansas | M&A |
| Missouri Kansas Texas | MKT |
| Missouri Pacific | MP |
| Mobile Oil Company | MOBX |
| Morenci Southern | MS |
| Moscow Camden & San Augustine | MC&SA |
| Nahma & Northern (Michigan) | N&N |
| Nationales de Mexico | NdeM |
| Nevada Central | NC |
| Nevada Copper Belt | NCB |
| Nevada Northern Railway | NN |
| New Haven | NH |
| New York Central | NYC |
| New York Ontario & Western | NYO&W |
| New York Susquehana & Western | NYS&W |
| New Zealand Railways | NZR |
| Nickel Plate (New York, Chicago & St Louis) | NKP |
| Norfolk & Western | N&W |
| Northern Alberta Railway | NAR |
| Northern Pacific | NP |
| Oahu Railway | Oahu |
| Okinawa Railway | Okinawa |
| Oklahoma Railway | ORy |
| Old Sydney Collieries Ltd, Nova Scotia | OSC |
| Pacific Electric | PE |
| Pacific Fruit Express | PFE |
| Pacific Lumber Co | PLC |
| Pagosa Lumber Co | Pagosa Lumber |
| Peninsula Terminal Co (Portland Oregon) | PTRC |
| Pennsylvania | PRR |
| Pere Marquette | PM |
| Pickering Lumber Co | Pickering |
| Pittsburgh & Lake Erie | P&LE |
| Pittsburgh & West Virginia | P&WV |
| Port Huron & Detroit | PHD |
| Pueblo Tramway | Pueblo |
| Pullman | Pullman |
| Pure Carbonic Co | DICX |
| Rail Box | RBOX |
| Rapid City Black Hills & Western | RCBH&W |
| Rayonier | Ray |
| Reading | RDG |
| Ringling Brothers & Barnham & Bailey Circus | RBBB |
| Rio Grande & San Juan | RG&SJ |
| Rio Grande Southern | RGS |
| Rio Grande Western | RGW |
| Rutland Railway | R |
| Salt Lake & Utah | SLU |
| San Diego & Arizona Eastern | SD&AE |
| San Luis Central | SLC |
| San Luis Valley Southern | SLVS |
| Santa Fe | AT&SF |
| Santa Maria Valley | SMV |
| several | several |
| Shippers Car Line Corp | SHPX |
| Sierra Railroad | Sierra |
| Silverton Gladstone & Northerly | SG&N |
| Silverton Northern | SN |
| Silverton Railroad | SRR |
| Southern Pacific | SP |
| Southern Pine Lumber | SPL |
| Sperry Rail Services | SRS |
| Spokane International | SI |
| St Johnsbury & Lake Champlain | SJ&LC |
| St Louis Iron Mountain & Southern | StLIM&S |
| St Louis San Francisco (Frisco) | SLSF |
| St Louis Southwestern ("Cotton Belt") | SSW |
| Sumpter Valley | SV |
| Sydney & Louisburg Railway (Nova Scotia) | S&L |
| Texaco | TCX |
| Texas & Pacific | T&P |
| Treasury Mountain | TM |
| Uintah | URy |
| Union Pacific | UP |
| Union Pacific Denver & Gulf | UPD&G |
| Union Refrigerator Transit | URTX |
| Union Tank Line | UTLX |
| US Army | USArmy |
| US Army | USAX |
| Utah Construction Company | UCC |
| Utah Idaho Central | UIC |
| Utah Railway | Utah |
| Valley & Siletz RR Co | V&S |
| Virginia & Truckee Railroad | V&T |
| Virginian | Vir |
| Wabash | Wab |
| Washington Central Railroad Co. Inc. | WCRC |
| Western Maryland | WM |
| Western Pacific | WP |
| Western Union Company | WU |
| Westside Lumber | WSL |