| Class I |
| Amtrak (AMTK) |
| BNSF Railway (BNSF) |
| CSX Transportation (CSXT) |
| Canadian National Railway (CN) |
| Kansas City Southern Railway (KCS) |
| Norfolk Southern Railway (NS) |
| Union Pacific Railroad (UP) |
| Class II |
| Alaska Railroad (ARR) |
| Buffalo and Pittsburgh Railroad (BPRR) |
| Central Oregon and Pacific Railroad (CORP) |
| Florida East Coast Railway (FEC) |
| Great Lakes Central Railroad (GLC) |
| Indiana Railroad (INRD) |
| Iowa Interstate Railroad (IAIS) |
| Kansas and Oklahoma Railroad (KO) |
| Long Island Rail Road (LI) |
| Montana Rail Link (MRL) |
| New York, Susquehanna and Western Railway (NYSW) |
| Paducah and Louisville Railway (PAL) |
| Providence and Worcester Railroad (PW) |
| Reading Blue Mountain and Northern Railroad (RBMN) |
| Toledo, Peoria and Western Railroad (BNSF Railway) (TPW) |
| Wheeling and Lake Erie Railway (WE) |
| Wisconsin and Southern Railroad (WSOR) |
| Class III |
| AT&L Railroad (ATLT) |
| Aberdeen, Carolina and Western Railway (ACWR) |
| Acadiana Railway (AKDN) |
| Aiken Railway (AIKR) |
| Akron Barberton Cluster Railway (AB) |
| Alabama & Tennessee River Railway (ATN) |
| Alabama Export Railroad (ALE) |
| Alabama Southern Railroad (ABS) |
| Alabama Warrior Railway (ABWR) |
| Alabama and Gulf Coast Railway (AGR) |
| Alamo Gulf Coast Railroad (AGCR) |
| Allegheny Valley Railroad (AVR) |
| Altamont Commuter Express Authority (ACEX) |
| Alton and Southern Railroad (Alton and Southern Railway) (ALS) |
| Angelina and Neches River Railroad (ANR) |
| Apache Railway (APA) |
| Appalachian and Ohio Railroad (AO) |
| Arizona Eastern Railway (AZER) |
| Arizona and California Railroad (ARZC) |
| Arkansas Midland Railroad (AKMD) |
| Arkansas Southern Railroad (ARS) |
| Arkansas and Missouri Railroad (AM) |
| Arkansas, Louisiana and Mississippi Railroad (ALM) |
| Arkansas-Oklahoma Railroad (AOK) |
| Ashland Railway (ASRY) |
| Atlantic and Western Railway (ATW) |
| Austin Western Railroad (AWRR) |
| Autauga Northern Railroad (AUT) |
| Bay Colony Railroad (BCLR) |
| Bay Line Railroad (BAYL) |
| Belt Railway of Chicago (BRC) |
| Big Four Terminal Railroad (BFT) |
| Bighorn Divide and Wyoming Railroad (BDW) |
| Blacklands Railroad (BLR) |
| Blackwell Northern Gateway Railroad (BNG) |
| Blue Ridge Southern Railroad (BLU) |
| Boise Valley Railroad (BVRR) |
| Boot Hill and Western Railway (BHWY) |
| Bountiful Grain and Craig Mountain Railroad (BGCM) |
| Brownsville and Rio Grande International Railroad (BRG) |
| Buckingham Branch Railroad (BB) |
| Buffalo Southern Railroad (BSOR) |
| Burlington Junction Railway (BJRY) |
| Butte, Anaconda and Pacific Railway (BAP) |
| California Northern Railroad (CFNR) |
| Caltrain (JPBX) |
| Camp Chase Industrial Railroad (CCRA) |
| Canadian Pacific Railway (CPRS) |
| Capital MetroRail (CMRX) |
| Carolina Coastal Railway (CLNA) |
| Cascade and Columbia River Railroad (CSCD) |
| CaterParrot Railnet (CPR) |
| Cedar Rapids and Iowa City Railway (Crandic) (CIC) |
| Central California Traction (CCT) |
| Central Florida Commuter Rail Transit (CFCR) |
| Central Illinois Railroad (CIRY) |
| Central Midland Railway (CMR) |
| Central Montana Rail (CM) |
| Central New England Railroad (CNZR) |
| Central New York Railroad (CNYK) |
| Central Railroad of Indiana (CIND) |
| Central Railroad of Indianapolis (CERA) |
| Chattooga and Chickamauga Railway (CCKY) |
| Chesapeake and Albemarle Railroad (CA) |
| Chicago Rail Link (CRL) |
| Chicago South Shore and South Bend Railroad (CSS) |
| Chicago, Ft. Wayne & Eastern Railroad (CFE) |
| Cimarron Valley Railroad (CVR) |
| Cincinnati Eastern Railroad (CCET) |
| Claremont Concord Railroad (CCRR) |
| Clarendon and Pittsford Railroad (CLP) |
| Cleveland Port Railway (CHB) |
| Cloquet Terminal Railroad (CTRR) |
| Columbia Basin Railroad (CBRW) |
| Columbia-Walla Walla Railway (CWW) |
| Columbus & Chattahoochee Railroad (CCH) |
| Columbus and Greenville Railway (CAGY) |
| Columbus and Ohio River Rail Road (CUOH) |
| Comstock Mountain Lion Railroad (CMLR) |
| Connecticut Southern Railroad (CSO) |
| Conrail Shared Assets Operations (CRCX) |
| Coopersville and Marne Railway (CPMY) |
| D&I Railroad (DAIR) |
| Dakota, Missouri Valley and Western Railroad (DMVW) |
| Dallas Area Rapid Transit (DART) |
| Dallas, Garland and Northeastern Railroad (DGNO) |
| Dardanelle and Russellville Railroad (DR) |
| De Queen and Eastern Railroad (DQE) |
| Decatur & Eastern Illinois Railroad (DREI) |
| Decatur Junction Railway (DT) |
| Delaware Lackawanna (DL) |
| Delmarva Central Railroad (DCR) |
| Delta Southern Railroad (DSRR) |
| Denver Rock Island Railroad (DRIR) |
| Depew, Lancaster and Western Railroad (DLWR) |
| Dover and Delware River Railroad (DD) |
| Dover and Rockaway River Railroad (DRRV) |
| East Brookfield & Spencer Railroad (EBSR) |
| East Camden and Highland Railroad (EACH) |
| Eastern Alabama Railway (EARY) |
| Eastern Idaho Railroad (EIRR) |
| Eastern Washington Gateway Railroad (EWG) |
| Eastside Freight Railroad (ESFR) |
| Elkhart and Western Railroad (EWR) |
| Ellis and Eastern (EE) |
| Escanaba and Lake Superior Railroad (ELS) |
| Evansville Western Railway (EVWR) |
| Falls Road Railroad (FRR) |
| Farmrail Corporation (FMRC) |
| Ferromex (FXE) |
| Fillmore and Western Railway (FWRY) |
| Finger Lakes Railway (FGLK) |
| Florida Gulf & Atlantic Railroad (FGA) |
| Florida Midland Railroad (FMID) |
| Fort Worth and Western Railroad (FWWR) |
| Garden City Western Railway (GCW) |
| Gary Railway Company (GRW) |
| Geaux Geaux Railroad (GOGR) |
| Georgetown Railroad (GRR) |
| Georgia Southern Railway (GS) |
| Georgia and Florida Railroad (GFRR) |
| Golden Triangle Railroad (GTRA) |
| Goose Lake Railway (GOOS) |
| Grainbelt Corporation (Farmrail) (GNBC) |
| Grand Elk Railroad (GDLK) |
| Grand Rapids Eastern Railroad (GR) |
| Great Northwest Railroad (GRNW) |
| Great Western Railway of Colorado (GWR) |
| Greater Shenandoah Valley Development (Shenandoah Valley Railroad) (SV) |
| Green Mountain Railroad (GMRC) |
| Grenada Railway (GRYR) |
| Hilton & Albany Railroad (HAL) |
| Housatonic Railroad (HRRC) |
| Huron and Eastern Railway (HESR) |
| Hutchinson and Northern Railway (HN) |
| ISG South Chicago and Indiana Harbor Railway (SCIH) |
| Idaho Northern and Pacific Railroad (INPR) |
| Illinois RailNet (IR) |
| Illinois and Midland Railroad (IMRR) |
| Indiana Harbor Belt Railroad (IHB) |
| Indiana Northeastern Railroad (IN) |
| Indiana Southern Railroad (ISRR) |
| Indiana and Ohio Railway (IORY) |
| Iowa Northern Railway (IANR) |
| Iowa Traction Railroad (IATR) |
| Ithaca Central Railroad (ITHR) |
| Jackson and Lansing Railroad (JAIL) |
| K.W.T. Railway (KWT) |
| Kanawha River Railroad (KNWA) |
| Kankakee, Beaverville and Southern Railroad (KBSR) |
| Kansas City Terminal Railway (KCTL) |
| Kasgro Rail Lines (KRL) |
| Keokuk Junction Railway (KJRY) |
| Kettle Falls International Railway (KFR) |
| Kiamichi Railroad (KRR) |
| Kiski Junction Railroad (KJR) |
| Klamath Northern Railway (KNOR) |
| Knoxville and Holston River Railroad (KXHR) |
| Kyle Railroad (KYLE) |
| Lackawanna Railway (LRWY) |
| Lake County Railroad (LCR) |
| Lake State Railway (LSRC) |
| Little Kanawha River Rail (LKRR) |
| Little Rock and Western Railroad (LRWN) |
| Livonia, Avon and Lakeville Railroad (LAL) |
| Logansport and Eel River Short-Line (LER) |
| Los Angeles Junction Railway (LAJ) |
| Louisiana Southern Railroad (LAS) |
| Louisiana and Delta Railroad (LDRR) |
| Louisiana and North West Railroad (LNW) |
| Louisville and Indiana Railroad (LIRC) |
| Lubbock & Western Railway (LBWR) |
| Luxapalila Valley Railroad (LXVR) |
| Luzerne Susquehanna Railway (LS) |
| Lycoming Valley Railroad (LVRR) |
| M and B Railroad (MNBR) |
| Mahoning Valley Railway (MVRY) |
| Manning Rail (MAN) |
| Marquette Rail (MQT) |
| Maryland Area Rail Commuter (MARC) |
| Massachusetts Bay Transportation Authority (MBTA) |
| Massachusetts Central Railroad (MCER) |
| Massachusetts Coastal Railroad (MC) |
| Massena Terminal Railroad (MSTR) |
| Metro-North Commuter Railroad (MNCW) |
| Michigan Shore Railroad (MS) |
| Middletown and New Jersey Railway (MNJ) |
| Minnesota Commercial Railway (MNNR) |
| Minnesota Northern Railroad (MNN) |
| Minnesota Northstar Metro Transit (MNRX) |
| Minnesota Prairie Line (MPLI) |
| Minnesota Southern Railway (MSWY) |
| Minnesota, Dakota and Western Railway (MDW) |
| Mission Mountain Railroad (MMT) |
| Mississippi Central (Illinois Central Gulf Railroad) (MSCI) |
| Missouri and Northern Arkansas Railroad (MNA) |
| Modoc Northern Railroad (MNRR) |
| Mohawk, Adirondack and Northern Railroad (MHWA) |
| Morristown and Erie Railway (ME) |
| Mount Vernon Terminal (MVT) |
| Mt. Rainier Railroad & Logging Museum (MRSR) |
| NJ Dept. Of Transportation (NJT) |
| Nashville Regional Transportation Authority (NRTX) |
| Nashville and Eastern Railroad (NERR) |
| Natchez Railway (NTZR) |
| Nebkota Railway (NRI) |
| Nebraska Central Railroad (NCRC) |
| Nebraska Northwestern Railroad (NNW) |
| Nebraska, Kansas and Colorado Railnet (NKCR) |
| New Castle Industrial Railroad (NCIR) |
| New England Central Railroad (NECR) |
| New Mexico Rail Runner Express (NMRX) |
| New Orleans Public Belt Railroad (NOPB) |
| New York New Jersey Rail (NYNJ) |
| New York and Atlantic Railway (NYA) |
| New York and Greenwood Lake Railway (NYGL) |
| New York and Lake Erie Railroad (NYLE) |
| New York and Ogdensburg Railway (NYOG) |
| Nittany and Bald Eagle Railroad (NBER) |
| Norfolk and Portsmouth Belt Line Railroad (NPB) |
| North County Transit District (NCTD) |
| North Louisiana & Arkansas Railroad (NLA) |
| North Shore Railroad (NSHR) |
| Northeast Illinois Regional Commuter Railroad (NIRC) |
| Northern Plains Railroad (NPR) |
| Northwestern Oklahoma Railroad (NOKL) |
| Ohi-Rail Corporation (OHIC) |
| Ohio Central Railroad (OHCR) |
| Ohio South Central Railroad (OSCR) |
| Ohio Southern Railroad (OSRR) |
| Oregon Pacific Railroad (OPR) |
| Otter Tail Valley Railroad (Genesee & Wyoming) (OTVR) |
| Pacific Harbor Line (PHL) |
| Pacific Sun Railroad (PSRR) |
| Paducah and Illinois Railroad (PI) |
| Palmetto Railways (PR) |
| Palouse River and Coulee City Railroad (PCC) |
| Pan Am Southern (PAS) |
| Panhandle Northern Railroad (PNR) |
| Pennsylvania & Southern Railway (PSCC) |
| Pennsylvania Northeastern Railroad (PN) |
| Piedmont and Northern Railway (Patriot Rail Corporation) (PNRW) |
| Pioneer Industrial Railway (PRY) |
| Plainsman Switching Company (PSC) |
| Plainview Terminal (PTC) |
| Port Authority Trans Hudson (PATH) |
| Port Authority Transit Corporation (PATC) |
| Port Harbor Railroad (PHRR) |
| Port Terminal Railroad Association (PTRA) |
| Portland and Western Railroad (PNWR) |
| Prescott and Northwestern Railroad (PNW) |
| Private (PVTX) |
| Progressive Rail (PGR) |
| Puget Sound and Pacific Railroad (PSAP) |
| R. J. Corman Tennessee Terminal (RJCK) |
| R.J. Corman Railroad Bardstown Line (RJCR) |
| R.J. Corman Railroad Central Kentucky Lines (RJCC) |
| R.J. Corman Railroad Cleveland line (RJCL) |
| R.J. Corman Railroad Memphis Line (RJCM) |
| R.J. Corman Railroad Western Ohio Line (RJCW) |
| Rapid City, Pierre & Eastern Railroad (RCPE) |
| Rarus Railway (RARW) |
| Red River Valley and Western Railroad (RRVW) |
| Republic Short Line (RSL) |
| Riceboro Southern Railway (RSOR) |
| Rochester and Southern Railroad (RSR) |
| Rock & Rail Inc. (RRRR) |
| Roscoe, Snyder and Pacific Railway (RSP) |
| Rusk, Palestine, & Pacific Railroad (RPP) |
| Rutland Line (RL) |
| SMS Rail Lines of New York (SNY) |
| SMS Rail Service (SLRS) |
| Sabine River and Northern Railroad (SRN) |
| San Diego Metropolitan Transit System (MTS) |
| San Diego Northern Railway (SDNR) |
| San Diego and Imperial Valley Railroad (SDIY) |
| San Joaquin Valley Railroad (SJVR) |
| Saratoga & North Creek Railway (SNC) |
| Semo Port Railroad (SE) |
| Shore Line East (SLE) |
| Sound Heavy Rail Transit (SDRX) |
| South Carolina Central Railroad (SCRF) |
| South Carolina Central Railroad (Georgia Southwestern Division) (GSWR) |
| South Central Florida Express (SCXF) |
| South Florida Rail Corridor (SFRC) |
| South Kansas and Oklahoma Railroad (SKOL) |
| South Plains Lamesa Railroad (SLAL) |
| Southeastern Pennsylvania Transportation Authority (SEPTA) (SEPA) |
| Southern California Regional Rail Authority (SCAX) |
| Southern Railroad of New Jersey (SRNJ) |
| Southwest Pennsylvania Railroad (SWP) |
| Southwestern Railroad (SW) |
| Spokane, Spangle and Palouse Railway (SSP) |
| Springfield Terminal Railway (Pan Am Railways) (ST) |
| Squaw Creek Southern Railroad (SCS) |
| St. Maries River Railroad (STMA) |
| Stillwater Central Railroad (SLWC) |
| Strasburg Rail Road (SRC) |
| Sunflour Railroad (SNR) |
| Tacoma Municipal Belt Line Railway (TMBL) |
| Tacoma Rail Mountain Division (TRMW) |
| Talley Rand Terminal Railroad (TTR) |
| Tennessee Overhill Heritage Association (TOHX) |
| Tennessee Southern Railroad (TSRR) |
| Terminal Railroad Association of St Louis (TRRA) |
| Terminal Railway Alabama State Docks (TASD) |
| Texas Gonzales and Northern Railway (TXGN) |
| Texas New Mexico Railway (TXN) |
| Texas North Western Railway (TXNW) |
| Texas Northeastern Division Mid-Michigan Railroad (TNER) |
| Texas Pacifico Transportation Limited (TXPF) |
| Texas Rock Crusher Railway (TXR) |
| Texas and Northern Railway (TN) |
| Texas and Oklahoma Railroad (TXOR) |
| Texas, Oklahoma and Eastern Railroad (TOE) |
| TimberRock Railroad (TIBR) |
| Tomahawk Railway (TR) |
| Transkentucky Transportation Railroad (TTIS) |
| Tri-Rail (TRCX) |
| Trinity Railway Express (TRE) |
| Tulsa-Sapulpa Union Railway (TSU) |
| Twin Cities and Western Railroad (TCWR) |
| Union Railroad Pittsburgh (URR) |
| Utah Central Railroad (UCRY) |
| Utah Railway (UTAH) |
| Utah Transit Authority (UTA) |
| V and S Railway (VSR) |
| Vermont Railway (VTR) |
| Vicksburg Southern Railroad (Watco) (VSOR) |
| Virginia Railway Express (VREX) |
| Wabash Central Railroad Corporation (WBCR) |
| West Tennessee Railroad Corporation (WTNN) |
| Western New York and Pennsylvania Railroad (WNYP) |
| Western Refrigerator Line (WRL) |
| Wichita Tillman and Jackson Railway Inc (WTJR) |
| Willamette and Pacific Railroad (WPRR) |
| Winchester and Western Railroad (WW) |
| Winston-Salem Southbound Railway (WSS) |
| Wisconsin Northern Railroad (WN) |
| Yadkin Valley Railroad (YVRR) |
| Yellowstone Valley Railroad (YSVR) |
| Youngstown Belt Railroad (YB) |
| Youngstown and Austintown Railroad (YARR) |
