| SA | Savannah & Atlanta Ry. Co. | 4/38-4/70 |
| Central of Georgia R.R. Co. | 1/75-1/80 | |
| Southern Ry. System | eliminated 1/91 | |
| Norfolk Southern Ry. Co. | added 1/91; 1/94-7/2000 | |
| SAAP | San Antonia and Aransas Pass Ry. (Southern Pacific Lines in Texas and Louisiana) | 4/38-1/52 |
| SABX | Southern Advance Bag & Paper Co. | eliminated 7/55 |
| Southern Advance Bag & Paper Division of Robert Gair Co., Inc. | added 7/55 | |
| Continental Can Co., Inc. | Oct-57 | |
| Continental Can Co., Inc., Southern Advance Paper Operation | eliminated 10/59 | |
| Continental Can Co., Inc. | added 10/59; 4/61-4/70; eliminated 4/74 | |
| SAC | Southern Alkali Corp. | Apr-38 |
| SACX | Columbia-Southern Chemical Corp. | 1/52-10/57; eliminated 4/61 |
| Pittsburgh Plate Glass Co. | added 4/61; 4/61-10/66; eliminated 4/68 | |
| PPG Industries, Inc. | added 4/68; 4/70; eliminated 10/72 | |
| SAFX | Safety-Kleen Corp. | added 4/97; 7/2000 |
| SAGX | The Smith Agricultural Chemical Co. | Apr-38 |
| SAL | Seaboard Coast Line R.R. Co. | 1/75-1/80; eliminated 1/83 |
| Seaboard System R.R., Inc. | added 1/83; eliminated 7/87 | |
| CSX Transportation, Inc. | added 7/87; 1/94-7/2000 | |
| SALX | General American Marks Co. | added 7/99; 7/2000 |
| SAMX | Seaboard Allied Milling Corp. | added 1/81; eliminated 4/82 |
| Seaboard Allied Milling Dept. of Cargill, Inc. | added 4/82; eliminated 7/84 | |
| Cargill, Inc. | added 7/84; 1/94-7/2000 | |
| SAN | Sandersville R.R. Co. | 7/65-1/94; added 4/97; 7/2000 |
| SANX | San Angelo Tank Car Line | 10/57-7/2000 |
| SAPT | Savannah Port Terminal R.R., Inc. | added 10/98; 7/2000 |
| SAQX | Southern Agricultural Tank Line | Apr-38 |
| SARX | Salyer Refining Co., Inc. | Jan-52 |
| Southern Appalachia Railway Museum | Jul-00 | |
| SASX | Southern Acid & Sulphur Co., Inc. | Apr-38 |
| Mathieson Chemical Corp. | Jan-52 | |
| Olin Mathieson Chemical Corp. | 10/57-4/61; eliminated 7/65 | |
| Suburban Fuel Tank Car Co. | added 7/65; 7/65-1/75; eliminated 1/79 | |
| Continental Tank Car Corp. | added 1/79; 1/80; eliminated 7/82 | |
| SATX | Standard Acid Works, Inc. (Standard Wholesale Phosphate & Acid Works, Inc.) | Apr-38 |
| City Public Service Board of San Antonio, Texas | 1/80-7/2000; eliminated 4/2001 | |
| City Public Service of San Antonio, Texas | added 4/2001 | |
| SAUX | Sauvage Gas Co. | added 1/65; 7/65-7/2000 |
| SAVX | Savannah Electric and Power Co. | added 10/96; 7/2000 |
| SAW | South Plains Switching Ltd. Co. | Jul-00 |
| SAWX | SAWCO, Inc. | eliminated 4/91 |
| Sawyer Gas of Jacksonville, Inc. | added 4/91; 1/94; eliminated 10/98; 7/2000 | |
| SAX | Simmons Oil & Refining Co. | 4/38-10/57 |
| Simmons Oil Corp. | Apr-61 | |
| SAZX | Saz Corp. | added 7/79; 1/80; eliminated 4/80 |
| Saz Transportation Corp. | added 4/80; 1/94-7/2000 | |
| SB | South Buffalo Ry. Co. | 1/52-1/94; eliminated 10/99; 7/2000 |
| SBC | Ferrocarril Sonora Baja California, S.A. de C.V. | 1/75-1/80 |
| Ferrocarril Sonora Baja California, S.A. de C.V. (transferred to Ferrocarriles Nacionales de Mexico) | eliminated 10/88 | |
| Ferrocarriles Nacionales de Mexico | added 10/88; 1/94-7/2000 | |
| SBCX | Armour Car Lines | added 1/60; 4/61 |
| North American Car Corp. | added 7/68; 4/70-1/75; eliminated 4/75 | |
| SBD | Seaboard System R.R., Inc. | added 1/83; eliminated 7/87 |
| CSX Transportation, Inc. | added 7/87; 1/94-7/2000 | |
| SBGX | NYTCO Leasing, Inc. | added 11/73; 1/75 |
| Transport Leasing Corp. | eliminated 1/77 | |
| Industry Leasing, Inc. | added 1/77; 1/80 | |
| Industry Financial Corp. | eliminated 7/92 | |
| SBIX | Standard Brands Inc., Tank Car Division | 1/52-10/66; eliminated 4/70 |
| Standard Brands Inc. | added 4/70; 1/75-1/80; eliminated 4/80 | |
| SBK | South Brooklyn Ry. Co. | 4/38-1/80; eliminated 10/92; 1/94 |
| SBLN | Sterling Belt Line Ry. | 1/94-7/2000 |
| SBLX | Sunbelt Chlor/Alkali Partnership | added 7/97; 7/2000 |
| SB&M | St. Louis, Brownsville & Mexico Ry. | 4/38-4/70 |
| SBM | St. Louis, Brownsville & Mexico | 1/75-1/80 |
| SBOX | Sherwood Brothers, Inc. | Apr-38 |
| SBPX | Koppers Co. | Apr-38 |
| SB&R | San Benito & Rio Grande Valley Ry. | 4/38-1/52 |
| SBRR | Stourbridge R.R. Co. | added 1/90; 1/94-7/2000 |
| SBVR | South Branch Valley Rail Road | added 10/78; eliminated 1/79; 1/80-7/2000 |
| SC | Sumter & Choctaw Ry. Co. | 1/75-1/80; eliminated 1/86 |
| SCAX | Shell Oil Co. of Canada, Ltd. | 4/38-1/52; eliminated 7/56 |
| Union Tank Car Co. | added 7/56; 10/57; eliminated 1/58 | |
| Shell Canada Ltd. | added 4/67; 4/70-1/80; eliminated 7/81 | |
| SCBG | Santa Cruz, Big Trees & Pacific Ry. Co. | 1/94-7/2000 |
| SCBX | Shell Oil Co. of British Columbia, Ltd. | Apr-38 |
| Standbridge Color Corp. | added 7/97; 7/2000 | |
| SCCX | Shell Oil Co., Inc. | 4/38-1/52; eliminated 10/53 |
| Shell Oil Co. | added 10/53; 10/57-1/80; eliminated 1/80 | |
| SCDX | Swift Canadian Co., Ltd. | 4/38-1/52 |
| SCEX | Southern California Edison Co. | added 10/58; 4/61-7/2000 |
| SCFE | South Central Florida R.R., Division of Brandywine Valley R.R. Co. | added 1/91; 1/94; eliminated 1/95; eliminated 4/95 |
| South Central Florida Express, Inc. | added 1/95; added 4/95; 7/2000 | |
| SCFS | Straits Car Ferry Service Corp. | Jan-80 |
| SCGX | Schuler Grain Co. | 1/80; eliminated 4/90 |
| Eades Commodities Co. | added 4/90; 1/94; eliminated 7/2000 | |
| General Electric Rail Services Corp. | added 7/2000; 7/2000 | |
| SCHX | Stauffer Chemical Co., Inc. (Eastern Branch) | 4/38-1/52; eliminated 7/56 |
| Stauffer Chemical Co. (Eastern Branch) | added 7/56; 10/57-1/80 | |
| Stauffer Chemical Co. | eliminated 4/90 | |
| Rhone-Poulenc Basic Chemicals Co. | added 4/90; 1/94; eliminated 10/99 | |
| Rhodia, Inc. | added 10/99; 7/2000 | |
| SCIX | Samuel Cabot Inc. | 4/38-4/70; eliminated 7/70 |
| Skeena Celluose, Inc. | added 10/87; 1/94; eliminated 7/94 | |
| General Electric Railcar Services Corp. | added 7/94; eliminated 4/98; added 4/99; eliminated 1/2000 | |
| General Electric Rail Services Corp. | added 1/2000; 7/2000 | |
| SCJX | Spencer Chemical Co. | 1/52-4/61; eliminated 4/65 |
| Warren Petroleum Co. | added 4/65; 7/65-10/66 | |
| Warren Petroleum Corp. | eliminated 1/70 | |
| Gulf Oil Co.--U.S., Division of Gulf Oil Corp. | added 1/70; 4/70-1/80; eliminated 7/82 | |
| Gulf Refining and Marketing Co., Division of Gulf Oil Corp. | added 7/82 | |
| Chevron U.S.A., Inc. | 1/94; eliminated 4/96 | |
| Chevron Chemical Co. | added 4/96; 7/2000; eliminated 1/2001 | |
| Chevron Phillips Chemical Co. L.P. | added 1/2001 | |
| SCK | South Central Arkansas Ry., Inc. | added 7/82 |
| SCKX | Spring Creek Coal Co. | eliminated 10/86 |
| Northern Coal Transportation Co. | added 10/86; 1/94-7/2000 | |
| SCL | Seaboard Coast Line R.R. Co. | 4/70-1/80; eliminated 1/83 |
| Seaboard System R.R., Inc. | added 1/83; eliminated 7/87 | |
| CSX Transportation, Inc. | added 7/87; 1/94-7/2000 | |
| SCLX | Samuet Cabot, Inc. | Apr-38 |
| Standard Chemical Co., Ltd. | Apr-38 | |
| Standard Chemical, Ltd. | added 7/55; 10/57-1/75 | |
| Stanchem Division, PPG Industries Canada Ltd. | 1/80; eliminated 7/84 | |
| PPG Canada, Inc. | added 7/84; eliminated 10/84 | |
| PPG Canada, Inc., Industrial Chemicals | added 10/84; 1/94; eliminated 1/97 | |
| CanadianOxy Industrial Chemicals Limited Partnership | added 1/97; 7/2000 | |
| SCM | Strouds Creek & Muddlety R.R. | 1/75-1/94 |
| SCMX | Shell Chemical Co. | 4/38-1/52 |
| Shell Chemical Corp. | Oct-57 | |
| Shell Chemical Co., a Division of Shell Oil Co. | 4/61-10/66; eliminated 7/69 | |
| Shell Oil Co. | added 7/69; 4/70-7/2000 | |
| SCNX | Columbian Gasoline Corp. | 4/38-1/52 |
| South Carolina Electric & Gas Co. | added 1/99; 7/2000 | |
| SCOX | The Sco Tank Line, Inc. | Apr-38 |
| Scoular Bishop Grain Co. | added 4/79; 1/80 | |
| The Scoular Co. | 1/94; eliminated 10/99; 7/2000 | |
| SCPX | Shell Chemical Co., a Division of Shell Oil Co. | 7/65-10/66; eliminated 7/69 |
| Shell Oil Co. | added 7/69; 4/70-7/2000 | |
| SCRF | South Carolina Central R.R. Co., Inc. | added 4/88; 1/94-7/2000 |
| SCRX | Santa Clarita Railway d/b/a James Clark & Co. | Jul-00 |
| SCST | Seaboard Transportation Co., a Wholly Owned Subsidiary of the Seaboard Coast Line R.R. Co. | 1/94-7/2000 |
| SCSX | The CIT Group/Capital Finance, Inc. | added 10/98; 7/2000 |
| SCT | Sioux City Terminal Ry. | 1/75-7/2000 |
| SCTR | South Central Tennessee R.R. Co., Inc. | added 10/78; 1/80-1/94; eliminated 10/94 |
| South Central Tennessee R.R. Corp. | added 10/94; 7/2000; eliminated 4/2001 | |
| SCTRR, LLC | added 4/2000 | |
| SCWX | South Carolina Public Service Authority | added 4/79; 1/80-1/94; eliminated 1/99; 7/2000 |
| SCX | The Shasta Water Co. | 4/38-1/52 |
| SCXF | South Central Florida Express, Inc. | added 1/95; added 4/95; 7/2000 |
| SCXY | St. Croix Valley R.R. Co. | added 1/98; 7/2000 |
| SCYX | Farmers Cooperative Association of York, Nebraska | added 4/81; eliminated 7/88 |
| U.S. Rail Services, Inc. | added 7/88; 1/94; eliminated 4/94 | |
| USL Capital Rail Services | added 4/94; eliminated 10/96 | |
| First Union Rail | added 10/96; 7/2000 | |
| SDAE | San Diego and Arizona Eastern Ry. Co. | 4/38-1/75; eliminated 1/80 |
| San Diego and Arizona Eastern Ry. Co., Kyle Santa Rosa, Inc.--Operation-Over | added 1/80; 1/80; eliminated 4/80; eliminated 10/80 | |
| San Diego and Arizona Eastern Transportation Co. | added 10/80 | |
| SDCX | Southern Dyestuff Corp. | 1/52-10/57; eliminated 1/58 |
| Smith-Douglass Co., Inc. | 7/65; eliminated 10/65 | |
| Smith-Douglass, a Division of the Borden Chemical Co. | added 10/65; 10/66; eliminated 10/69 | |
| Smith-Douglass, a Division of Borden Chemical, Borden, Inc. | added 10/69; 4/70; eliminated 1/72 | |
| Borden Chemical, Division of Borden, Inc. | added 1/72; 1/75-1/80 | |
| AMAX Phosphate, Inc. | added 7/81 | |
| AMAX Chemical Corp. | eliminated 1/88 | |
| Consolidated Minerals, Inc., Feed Supplement Division | added 1/88; 1/94-7/2000 | |
| SDEX | Swindell-Dresser Energy Supply Co. | 1/80-7/2000; eliminated 4/2001 |
| Savage-Harrington Energy | added 4/2001 | |
| SDIT | San Diego & Imperial Valley Ry. Co. | added 10/84 |
| SDIX | Smith-Douglass Co., Inc. | 1/52; eliminated 4/57 |
| SDIY | San Diego & Imperial Valley R.R. Co. | eliminated 10/92; 1/94-7/2000 |
| SDPX | South Dakota Soybean Processors, Inc. | added 4/97; eliminated 1/99; added 7/2000; 7/2000 |
| SDRX | Sinclair Refining Co. | 4/38-1/52; eliminated 1/58 |
| Union Tank Car Co. | 10/57; added 1/58; 4/61-4/70; eliminated 7/73 | |
| Central Puget Sound Regional Transit Authority | Jul-00 | |
| SDX | Squire Dingee Co. | 4/38-4/61 |
| SE | Ferrocarrils Unidos del Sureste, S.A. de C.V. | 1/75-1/80 |
| Semo Port R.R., Inc. | added 1/95; 7/2000 | |
| SEAX | Seahorse Fuels, Inc. | added 1/62; 7/65-4/70 |
| SECX | Southern Extract Co. (The Mead Corp.) | Apr-38 |
| South-East Coal Co. | added 1/75; 1/75-1/80; eliminated 7/93; 1/94 | |
| General Electric Railcar Services Corp. | eliminated 1/2000 | |
| General Electric Rail Services Corp. | added 1/2000; 7/2000 | |
| SEFX | North American Rails Leasing Corp. | added 1/99; 7/2000 |
| SEGX | Eades Commodity Co. | added 7/2000; 7/2000 |
| SEI | Southeastern International Corp. | Jul-00 |
| SEIX | Seimax Gas Corp. | added 11/73; 1/75-1/94; eliminated 7/97; 7/2000 |
| SEKR | Southeast Kansas R.R. Co. | added 10/88; 1/94; eliminated 10/96; 7/2000 |
| SEMX | Seminole Electric Cooperative, Inc. | added 1/83; 1/94-7/2000 |
| SEPA | Southeastern Pennsylvania Transporation Authority (passenger commuter operation) | 1/94-7/2000 |
| SEPX | Shell Eastern Petroleum Products (Shell Union Oil Corp.) | Apr-38 |
| SEPX | Southwestern Electric Power Co. | 1/80-7/2000 |
| SEQX | Sequa Chemicals, Inc. | added 4/97; 7/2000 |
| SERA | Sierra R.R. Co. | 1/75-1/80; eliminated 1/88; eliminated 10/91; 1/94-7/2000 |
| SERX | Service Tank Car Co. | Apr-38 |
| Shippers' Car Line Corp. (Service Tank Car Co.) | Jan-52 | |
| Shippers' Car Line Corp. | eliminated 7/56 | |
| Shippers' Car Line Division of ACF Industries, Inc. | added 7/56; 10/57-1/80; eliminated 4/88 | |
| ACF Industries, Inc. | added 4/88; 1/94-7/2000 | |
| SESX | Sessions Co., Inc. | 1/52-4/61 |
| SESX | B.C. Hydro | added 1/90; eliminated 1/94; 7/2000 |
| SFAL | SF&L Ry., Inc. | 1/94-7/2000 |
| SFB | San Francisco Belt | Jan-94 |
| SFCX | Sheffield Farms Co., Inc. | Apr-38 |
| Southern Fertilizer and Chemical Co. | Oct-57 | |
| SFDX | Southern Fruit Distributors, Inc. | 1/52-4/61; eliminated 1/65 |
| SFIX | System Fuels, Inc. | 1/80; added 4/80; 1/94; eliminated 4/98 |
| HELM Financial Corp. | added 4/98; 7/2000 | |
| SFLC | Atchison, Topeka & Santa Fe Ry. Co. | added 7/77; 1/80-1/94; eliminated 7/97 |
| Burlington Northern Santa Fe Ry. Co. | added 7/97; 7/2000 | |
| SFLR | The Shore Fast Line, Inc. | eliminated 7/92; 1/94-7/2000 |
| SFPP | Spruce Fall Power & Paper | 1/75-1/80 |
| SFQ | The Burlington Northern Santa Fe Ry. Co. | Jul-00 |
| SFR | Southern Freight Logistics, LLC d/b/a Southern Freight R.R. | Jul-00 |
| SFRA | Atchison, Topeka & Santa Fe Ry. | 7/65-1/75 |
| SFRB | Atchison, Topeka & Santa Fe Ry. | 10/57-1/80; eliminated 1/86 |
| SFRC | Atchison, Topeka & Santa Fe Ry. Co. | 4/61-1/94; eliminated 7/97 |
| Burlington Northern Santa Fe R.R. Co. | added 7/97 | |
| SFRD | Atchison, Topeka & Santa Fe Ry. Co. | 4/38-1/80; eliminated 7/80 |
| SFRE | Atchison, Topeka & Santa Fe Ry. | 7/65-1/80; eliminated 1/86 |
| SFRF | Atchison, Topeka & Santa Fe Ry. | 10/66-1/75 |
| SFRM | Atchison, Topeka & Santa Fe Ry. | 7/65-1/75 |
| SFRP | Atchison, Topeka & Santa Fe Ry. | 7/65-1/80; eliminated 1/81 |
| SFRX | Southern Foundry Supply, Inc. | added 10/96; eliminated 4/2000; 7/2000 |
| Philip Metals, Inc. | added 4/2001 | |
| SFS | Santa Fe Southern Ry., Inc. | added 7/92; eliminated 1/94; eliminated 1/98; 7/2000 |
| SFSX | San Francisco Transportation Services Co. | added 1/78; eliminated 10/78 |
| San Francisco Transportation Services Co., Inc. | added 10/78; 1/80; eliminated 10/83; 1/94-7/2000 | |
| SFT | Springfield Terminal Ry. (Illinois) | 4/38-1/52 |
| SFTX | Suburban Fuel Tank Car Co. | 4/61-1/75; eliminated 1/79 |
| Continental Tank Car Corp. | added 1/79; 1/80-7/2000 | |
| SFX | Southern Fertilizer & Chemical Co. | Apr-38 |
| Stokely Foods, Inc. | Jan-52 | |
| SGAX | SGA Leasing Co. | 1/94-7/2000 |
| SGCX | Sungas Corp. of Florida | added 1/74; 1/75-7/2000 |
| SGIX | Werner's, Inc. | added 1/62; 7/65-1/80; eliminated 4/80 |
| LPG Transportation, Inc. | added 4/80; eliminated 1/91 | |
| Suburban Gas, Inc. | added 1/91; eliminated 4/91 | |
| Vision Energy Minnesota, Inc. | added 4/91; eliminated 10/91; 1/94-7/2000 | |
| SGLR | Seminole Gulf Ry. L.P. | added 4/88; 1/94-7/2000 |
| SGRX | Skip Gibbs | Jul-00 |
| SGSX | Sure-Grow Solutions, Inc. | added 10/89; 1/94; eliminated 10/94 |
| SGSX | Terra International, Inc. | Jul-00 |
| SGVY | Saginaw Valley Ry. Co., Inc. | 1/94-7/2000 |
| SH | Steelton & Highspire R.R. Co. | 1/75; added 1/80; 1/80-1/94; eliminated 10/99; 7/2000 |
| SHLX | Procor Ltd. | added 1/98; 7/2000 |
| SHPX | Shippers' Car Line Corp. | 4/38-1/52; eliminated 7/56 |
| Shippers' Car Line Division of ACF Industries, Inc. | added 7/56; 10/57-1/80; eliminated 4/88 | |
| ACF Industries, Inc. | eliminated 4/88; eliminated 10/93; 1/94; added 7/97; 7/2000 | |
| SI | Spokane International R.R. Co. | 1/75-1/80; added 1/88 |
| Union Pacific R.R. Co. | added 4/88; 1/94; eliminated 4/94; 7/2000 | |
| SICX | Sloss Industries Corp. | added 7/88; 1/94-7/2000 |
| SIEX | Southern Iron & Equipment Co. | added 10/70 |
| Southern Iron & Equipment Co., Division U.S. Railway Manufacturing Co. | 1/75; eliminated 7/77 | |
| Southern Iron & Equipment Co., Division Evans Transportation Co. | added 7/77; eliminated 7/79 | |
| United States Leasing Co. | added 7/79; 1/80 | |
| United States Railway Leasing Co. | eliminated 10/80 | |
| Southeastern Industrial Enterprises, Inc. | added 4/95; 7/2000 | |
| SIGX | Southern Indiana Gas and Electric Co. | added 4/79; 1/80-7/2000 |
| SILX | The Silurian Oil Co. (W.C. McBride, Inc.) | Apr-38 |
| Jeffersonville Silgas, Inc. | 1/52-10/66; eliminated 10/69 | |
| SIMX | North American Car Corp. | added 7/64; 7/65-4/70 |
| Sierra Bag Co. | added 1/83; eliminated 1/89 | |
| SIND | Southern Indiana Ry., Inc. | 1/75-1/80; eliminated 7/89; 1/94-7/2000 |
| SIPX | Arrendadora Sipco, S.A. de C.V. | added 7/94; 7/2000 |
| SIR | Staten Island Rapid Transit Ry., Co. | 4/38-4/70 |
| SIRC | Staten Island R.R. Corp. | 1/75-1/80 |
| SIRR | Southern Industrial R.R., Inc. | 1/75-7/2000 |
| SIRX | Southern Illinois Railcar Co. | added 1/91; 1/94-7/2000 |
| SIRY | Staten Island Ry. Corp. (transferred to New York, Susquehanna and Western Ry. Corp.) | eliminated 10/88 |
| Staten Island Ry. Corp. | eliminated 4/92; 1/94 | |
| SITX | Sherritt International Corp. | added 4/97; 7/2000 |
| SJB | St. Joseph Belt Ry. Co. | 4/38-1/75 |
| SJEX | SJEX, Inc. | added 7/86; eliminated 1/90; 1/94-7/2000 |
| SJGI | St. Joseph & Grand Island Ry. | 4/38-1/52 |
| SJ&L | St. Johnsbury & Lake Champlain R.R. Co. | Apr-38 |
| SJL | St. Johnsbury & Lamoille County R.R. | 4/61-4/70; eliminated 11/73; added 4/74; 1/75; eliminated 7/77 |
| Vermont Northern R.R. Co. | added 1/78; eliminated 4/78 | |
| SJLX | St. Joseph Lead Co. | 4/61-4/70; eliminated 10/70 (reporting marks changed to SJMX) |
| SJMX | St. Joe Minerals Corp. (name changed to Zinc Corp. of America, reporting marks to ZCAX) | added 10/70; 1/75-1/80; eliminated 10/88 |
| SJNX | Mobay Corp. | 1/94-7/2000 |
| SJRT | St. Johns River Terminal | 1/75-7/2000 |
| SJRX | Jacksonville Electric Authority | added 10/86; 1/94; eliminated 1/95; 7/2000 |
| SJT | St. Joseph Terminal R.R. Co. | 1/75-1/80 |
| SJVR | San Joaquin Valley R.R. Co. | added 4/92; 1/94-7/2000 |
| SJWX | Transportation Management, Inc. | 1/75; added 4/75 |
| Missouri Valley Walnut Co. | 1/80; eliminated 1/82 | |
| SKCX | Sinclair-Koppers Co. | added 1/68; 4/70 |
| ARCO Polymers, Inc. | 1/75-1/80; eliminated 10/82 | |
| ARCO Chemical Co. | added 10/82; 1/94-7/2000 | |
| SKGX | Sibley Railcar & Pats, Inc. | Jul-00 |
| SKNX | The Saskatchewan Grain Car Corp. | added 1/81; 1/94-7/2000 |
| SKOL | South Kansas & Oklahoma R.R., Inc. | added 4/92; 1/94; eliminated 1/97; added 7/98; 7/2000 |
| SKPR | Southern Kent & Pacific R.R. Co. | 1/94-7/2000 |
| SKPX | The Saskatchewan Grain Car Corp. | added 1/81; 1/94-7/2000 |
| SKRX | Schuylkill Railcar L.P. | added 10/98; 7/2000; eliminated 7/2000 |
| SKX | Spencer Kellogg & Sons, Inc. | Apr-38 |
| S&L | Sydney & Louisburg Ry. | 4/38-4/61 |
| Cumberland Ry. | Jul-65 | |
| SL | Sugar Land Ry. | 4/38-1/52 |
| Salt Lake City Southern R.R. Co., Inc. | 1/94-7/2000 | |
| SLAL | South Plains Lamesa R.R., Ltd. | Jul-00 |
| SLAW | St. Lawrence R.R., Division of National Railway Utilization Corp. | Jan-80 |
| St. Lawrence R.R. | eliminated 7/90 | |
| SLAX | St. Lawrence Starch Co. Ltd. | 4/38-1/80; eliminated 10/87 |
| SLC | San Luis Central R.R. | Jan-52 |
| The San Luis Central R.R. Co. | 1/75-7/2000 | |
| SLEX | Short Line Enterprises, Ltd. | 1/94-7/2000 |
| SLGG | Sidney & Lowe R.R., Inc. | added 10/83; eliminated 4/89; eliminated 4/91; added 7/92; 1/94; eliminated 4/97 |
| Progress Rail Services Corp. d/b/a Sidney & Lowe R.R., Inc. | added 4/97; 7/2000 | |
| SLGW | Salt Lake, Garfield and Western Ry. Co. | 1/75-1/80; eliminated 4/89; 1/94-7/2000 |
| SL&H | St. Louis & Hannibal R.R. Co. | Apr-38 |
| SLH | St. Louis & Hannibal Ry. | Jan-52 |
| SL&L | Salt Lake, Garfield & Western Ry. Co. | Apr-38 |
| SLOF | St. Louis and O'Fallon Ry. | 4/38-1/52 |
| SLOX | Selox, Inc. | eliminated 7/92 |
| SLQ | St. Lawrence & Atlantic R.R. (Quebec) Inc. | Jul-00 |
| SLR | St. Lawrence & Atlantic R.R. Co. | added 10/89; 1/94-7/2000 |
| SLRR | St. Lawrence & Raquette River R.R. | added 7/90; eliminated 1/94 |
| SLRS | SMS Rail Service, Inc. | Jul-00 |
| SLRX | St. Louis Refrigerator Car Co. | 4/38-4/70; eliminated 4/73; added 1/74; 1/75; eliminated 1/75; 1/80; eliminated 4/81 |
| SLS | Sea-Land Service, Inc. | Jan-75 |
| SLSF | St. Louis-San Francisco Ry. Co. | 4/38-1/80; eliminated 1/81; 7/2000 |
| Burlington Northern Inc. | added 1/81; eliminated 7/81 | |
| Burlington Northern R.R. Co. | added 7/81; 1/94 | |
| SLSX | Swift Live Stock Express (General American Transportation Corp.) | Apr-38 |
| General American Transportation Corp. | 1/52-7/65 | |
| Swift Live Stock Express (General American Transportation Corp.) | 10/66; eliminated 1/70 | |
| SLTX | Slade Transport, Inc. | added 7/74; 1/75-1/80; eliminated 4/87 |
| SLU | Salt Lake & Utah R.R. | 4/38-1/52 |
| SLVX | Silver Enterprises | Jul-00 |
| SLWC | Stillwater Central R.R. Co., Inc. | Jul-00 |
| SM | St. Marys R.R. Co. | 1/75; eliminated 1/79; 1/80-7/2000 |
| SMA | San Manuel Arizona R.R. Co. | 1/75-7/2000 |
| SMAX | Siemens-Allis, Inc. | added 4/85; eliminated 4/86 |
| SMAX | Siemens | added 4/86; eliminated 10/88 |
| SMCX | The Altus Co. | added 1/62 |
| Standard Milling Co. | 7/65-4/70; eliminated 4/72 | |
| San Miguel Electric Cooperative, Inc. | added 10/81; 1/94-7/2000 | |
| SMEX | South Mississippi Electric Power Association | added 1/78; 1/80-7/2000 |
| SMIX | Schreiber Mills, Inc. | added 7/59; 4/61-1/75; eliminated 7/76 |
| Structural Metals, Inc. | added 1/86; 1/94-7/2000 | |
| SMMX | St. Marys Cement Co. | 1/94-7/2000 |
| SMNR | Southern Manitoba Ry., Inc. | Jul-00 |
| SMNX | Solvay Minerals, Inc. | Jul-00 |
| SMOX | Standard Molasses Co. | 1/52; eliminated 10/57 |
| SMPX | Shell-Mex Oil Co. of Cuba, Ltd. (Cia Petrolera Shell--Mex de Cuba, S.A.) | Apr-38 |
| Commercial Metals Co. | added 1/97; added 4/97; 7/2000 | |
| SMRR | Sisseton Milbank R.R. Inc. | added 10/89; 1/94-7/2000 |
| SMRX | Sampierre Chemical Corp. | added 10/60; 4/61 |
| Atlanta Chapter--National Railway Historical Society, Inc. | Jul-00 | |
| SMSX | S. Morgan Smith Co. | 4/38-10/57 |
| SMV | Santa Maria Valley R.R. Co. | 1/75-7/2000; eliminated 10/2000 |
| SMX | Staley Milling Co. | Jan-52 |
| Socony Mobil Oil Co., Inc. | 10/57-4/61 | |
| SN | Sacramento Northern Ry. | 10/57-1/80; eliminated 10/87 |
| Union Pacific R.R. Co. | added 10/87; eliminated 4/88 | |
| SNAX | Sociedad Nacional de Productores de Alcohol | 1/52-1/75 |
| SNBL | Sioux City & New Orleans Barge Line | 1/75-7/2000 |
| SNCO | Seaport Navigation | 1/75-1/80 |
| SNCT | Seattle & North Coast R.R. Co. | added 4/80; eliminated 1/89 |
| SNFX | Shell Chemical Co., a Division of Shell Oil Co. | added 10/66; 10/66; eliminated 7/69 |
| Shell Oil Co. | added 7/69; 4/70-1/80; eliminated 1/83 | |
| IND/AG Chemicals, Inc. | added 1/83; 1/94-7/2000 | |
| SNGX | Southeastern Natural Gas Corp. | added 4/62 |
| Tropigas Inc. of Florida | 7/65; eliminated 1/66 | |
| SNHX | Shell Chemical Corp. | Oct-57 |
| Shell Chemical Co., a Division of Shell Oil Co. | 4/61-10/66; eliminated 7/69 | |
| Shell Oil Co. | added 7/69; 4/70-1/80; eliminated 1/83 | |
| IND/AG Chemicals, Inc. | added 1/83; 1/94-7/2000 | |
| SNX | National Car Co. | 1/52-7/65 & 4/70; eliminated 7/70 |
| Stadler's Packing Co., Columbus, Ind. (National Car Co.) | Oct-66 | |
| S&NY | Susquehanna & New York R.R. Co. | Apr-38 |
| SO | South Orient R.R. Co., Ltd. | added 1/93; 1/94; eliminated 7/94 |
| South Orient | added 1/97; eliminated 7/97; 7/2000 | |
| SOCX | Sohio Oil Co. | Jan-94 |
| BP Oil Co. | added 7/95 | |
| BP Amoco Chemical Co. | eliminated 1/2000 | |
| BP Amoco Chemical Co., BP Oil Division | added 1/2000; 7/2000 | |
| SOEX | Shell Oil Co. | added 7/64; 7/65-7/2000 |
| SOGX | The Shamrock Oil and Gas Corp. | 1/52-10/66; eliminated 4/68 |
| Diamond Shamrock Corp. | added 4/68; 4/70-1/80 | |
| Diamond Shamrock Chemicals Co. | eliminated 7/84 | |
| SOIX | Standard Oil Co. (Indiana) | Jan-52 |
| Sand Seed Service, Inc. | added 4/80; eliminated 10/92; 1/94-7/2000 | |
| SOLX | Standard Oil Co. (Indiana) | Apr-38 |
| Superior Oil Works | Apr-38 | |
| Solano Rail Car Co. | 1/75-1/80 | |
| Solano Rail Car Corp. | added 4/80; eliminated 7/89 | |
| Solite Corp. | Jul-00 | |
| SOM | Somerset R.R. Corp. | 1/94-7/2000 |
| SONX | Sonford Products Corp. | added 1/65; 7/65-4/70; eliminated 4/71 |
| Agtrans Corp. | added 10/86; eliminated 7/91 | |
| Soneco Service, Inc. | added 7/91; eliminated 7/92; 1/94-7/2000 | |
| SOO | Minneapolis, St. Paul & Sault Ste. Marie Ry. Co. | 4/38-4/61 |
| Soo Line R.R. Co. | 7/65-7/2000 | |
| SOPR | South Pierce R.R. | 1/80-7/2000 |
| SORA | Southern Rails Cooperative, Ltd. | 1/94-7/2000 |
| SOSX | Southern Oil Service | Apr-38 |
| SOT | South Omaha Terminal Ry. Co. | 1/75; eliminated 7/78 |
| SOTX | Stoll Oil Refining Co., Inc. | 4/38-1/52 |
| Southern Concrete Construction Co., Inc. | added 10/97; eliminated 1/98; 7/2000 | |
| SOU | Southern Ry. System | 1/75-1/80; eliminated 1/91 |
| Norfolk Southern Ry. Co. | added 1/91; 1/94-7/2000 | |
| SP | Southern Pacific Co. (Pacific Lines) | 1/52-7/65 |
| Southern Pacific Co. | Oct-66 | |
| Southern Pacific Co. (Pacific Lines) | Apr-70 | |
| Southern Pacific Transportation Co. | 1/75-1/94; eliminated 10/98 | |
| Union Pacific R.R. Co. | added 10/98; 7/2000 | |
| SPAX | Atlas Pipeline Corp. | Apr-38 |
| Southeastern Pennsylvania Transportation Authority | added 10/84; eliminated 4/90; 1/94-7/2000 | |
| SPCH | Quest Communications Corp. | Jul-00 |
| SPCX | Superior Packing Co. (National Car Co.) | Apr-38 |
| Saskatchewan Power Corp. | added 7/78; 1/80; eliminated 10/82 | |
| SP Construction Services | added 1/97; eliminated 4/98 | |
| Qwest Communications Corp. | added 4/98; eliminated 7/98; 7/2000 | |
| SPDX | Sterling Products Co. | Apr-38 |
| SPEC | Spencerville and Elgin R.R. Co. | added 4/78; added 10/78 |
| SPEG | Van Wert County-Allen County Port Authorities d/b/a Spencerville and Elgin R.R. Co. | eliminated 10/84 |
| Van Wert County Port Authority-Port Authority of Allen County d/b/a Spencerville and Elgin R.R. Co. | added 10/84; eliminated 4/85 | |
| Spencerville and Elgin R.R. Co. | 1/80; added 4/85; eliminated 10/91 | |
| SPEX | Southern Pine Extracts Co. | 1/52-10/57; eliminated 7/60 |
| SPFE | Southern Pacific Transportation Co. | 1/75-1/94; eliminated 10/98 |
| Union Pacific R.R. Co. | added 10/98; 7/2000 | |
| SPGX | Suburban Propane--Division of Quantum Chemical Corp. | added 10/95; eliminated 4/97 |
| Suburban Propane L.P. | added 4/97; 7/2000 | |
| SPIX | Sweeteners Plus, Inc. | Jul-00 |
| SPKX | Shawinigan Products Corp. | 4/38-4/70; eliminated 4/73 |
| SPM | Southern Pacific R.R. of Mexico | 4/38-1/52 |
| SPMX | Springfield Missouri Packing Co. | Apr-38 |
| SPNX | Suburban Propane Nat-Gas Co. of New Jersey | eliminated 4/57 |
| Suburban Propane Gas Corp. | added 4/57; 10/57-10/66; eliminated 7/69 | |
| SPQ | Southern Pacific Transportation Co. | added 7/88; 1/94 |
| Union Pacific R.R. Co. | Jul-00 | |
| SPRX | Seaport Central R.R., Inc. | Jul-00 |
| SP&S | Spokane, Portland & Seattle Ry. Co. | Apr-38 |
| SPS | Spokane, Portland & Seattle Ry. Co. | 1/52-10/66 |
| Spokane, Portland & Seattle Ry. (Burlington Northern) | Apr-70 | |
| Burlington Northern Inc. | 1/75-1/80; eliminated 7/81 | |
| Burlington Northern R.R. Co. | added 7/81; 1/94 | |
| The Burlington Northern Santa Fe Ry. Co. | Jul-00 | |
| SPSX | Stickney & Poor Spice Co. | Jan-52 |
| Steel Processing Services, Inc. | added 1/90; eliminated 10/93 | |
| Progress Rail Services Corp. | added 10/93; 1/94-7/2000 | |
| SPTX | Transcisco Leasing Co. | added 4/93; eliminated 7/93; 1/94 |
| Trinity Rail Management, Inc. | added 7/97; 7/2000 | |
| SPUD | St. Paul Union Depot Co. | 1/75-7/2000 |
| SPX | The Solvay Process Co. | Apr-38 |
| Solvay Process Division Allied Chemical and Dye Corp. | 1/52-10/57; eliminated 7/58 | |
| Solvay Process Division, Allied Chemical Corp. | added 7/58; 4/61; eliminated 7/64 | |
| SQVR | Sequatchie Valley R.R. | added 1/87; eliminated 10/91; 1/94-7/2000 |
| SR | SouthRail Corp. | added 7/88; 1/94; eliminated 7/94 |
| Kansas City Southern Ry. Co. | added 7/94; 7/2000 | |
| SRC | Strasburg R.R. Co. | 1/75-7/2000 |
| SRCX | Sid Richardson Carbon Co. | 1/52-7/2000 |
| SRDX | D-X Sunray Oil Co. | 10/57-4/61 |
| Sunray D-X Oil Co. | 7/65-10/66; eliminated 4/69 | |
| Sun Oil Co., D-X Division | added 4/69 | |
| Sunray D-X Oil Co. | eliminated 4/70 | |
| Sun Oil Co. | added 4/70; 4/70; eliminated 1/72 | |
| Sun Oil Co. of Pennsylvania | added 1/72; 1/75; eliminated 7/76; 1/80 | |
| SREX | REA Express, Inc. | eliminated 4/74 |
| StatesRail Equipment Co., LLC | Jul-00 | |
| SRIX | Southern Region Industrial Realty, Inc. | added 4/82; eliminated 10/89; 1/94 |
| Southwest Rail Industries, Inc. | added 10/98; 7/2000 | |
| SRLX | Swift Refrigerator Line (General American Transportation Corp.) | Apr-38 |
| General American Transportation Corp. | 1/52-7/65 | |
| Swift Refrigerator Line (General American Transportation Corp.) | Oct-66 | |
| General American Transportation Corp. | 4/70-1/80; eliminated 10/92 | |
| Southern Rail Leasing, Inc. | Jul-00 | |
| SRMX | United Technologies Chemical System Division | Jan-94 |
| SRN | Sabine River & Northern R.R. Co. | 1/75-7/2000 |
| SRNJ | Southern R.R. Co. of New Jersey | added 7/92; eliminated 1/94; 7/2000 |
| SROX | Savannah River Operations Office, Atomic Energy Commission | 10/57-7/65 |
| U.S. Atomic Energy Commission, Savannah River Operations Office | Oct-66 | |
| Savannah River Operations Office, Atomic Energy Commission | 4/70-1/75 | |
| United States Energy Research and Development Administration, Savannah River Operations Office | added 4/75; eliminated 1/78 | |
| U.S. Department of Energy, Savannah River Operations Office | added 1/78; 1/80; eliminated 1/91 | |
| SRPX | Rhinelander Division, St. Regis Paper Co. | added 1/68; 4/70-1/75 |
| Salt River Project Agricultural Improvement and Power District | added 7/78; 1/80; eliminated 10/89; 1/94-7/2000 | |
| SRRX | Star R.R. Equipment | added 1/71; 1/75-1/80; eliminated 7/92; 1/94-7/2000 |
| SRSX | Sperry Rail Service | Jul-00 |
| SRTX | Southwind Rail Travel Ltd. | Jul-00 |
| SRX | Sunland Refining Corp. | 4/38-10/66; eliminated 4/70 |
| SRY | Southern Ry. of British Columbia Ltd. | added 10/89; 1/94-7/2000 |
| SRYC | Sierra Ry. Co. of California | 1/94-7/2000 |
| SRYX | Stanray Corp. | 7/65-10/66; eliminated 10/68 |
| SS | Sand Springs Ry. Co. | 1/75-1/80; added 1/94; 7/2000 |
| SSAM | Sault Ste. Marie Bridge Co. | added 4/93; 1/94-7/2000 |
| SSC | Southern Switching Co. | added 1/95; eliminated 7/96; 7/2000 |
| SSCX | Southern States Chemical Co. | added 7/63; 7/65-10/66; eliminated 10/67 |
| Southern Stone Co., Inc. | added 4/71; 1/75; eliminated 7/79 | |
| SSDK | Savannah State Docks R.R. Co. | 1/75; added 4/79; 1/80-1/94; eliminated 1/99; 7/2000 |
| SSFX | Southern States Phosphate & Fertilizer Co. | 4/61-7/65; eliminated 4/66 |
| SSGX | South Soo Grain Co. | added 11/73; 1/75-1/80; eliminated 5/83 |
| McMaster Grain Co. | added 5/83; eliminated 4/90 | |
| SSH | South Shore | 1/75 & 1/94-7/2000 |
| SSIX | SSI Rail Corp. | eliminated 1/78 |
| Itel Corp., Rail Division | added 1/78; 1/80; eliminated 4/87 | |
| Itel Rail Corp. | added 4/87; eliminated 10/92 | |
| General Electric Railcar Services Corp. | added 10/92; 1/94; eliminated 1/2000 | |
| General Electric Rail Services Corp. | added 1/2000; 7/2000 | |
| SSJR | Sheffield Station Junction Ry. | Jul-00 |
| SSL | Skaneateles Short Line R.R. Corp. | 1/75-1/80; eliminated 10/81 |
| SSLV | Southern San Luis Valley R.R. Co. | 1/75-1/80; eliminated 1/94; 7/2000 |
| SSLX | Semet Solvay Co. | Apr-38 |
| Semet Solvay Division Allied Chemical and Dye Corp. | 1/52-10/57; eliminated 7/58 | |
| Semet Solvay Division, Allied Chemical Corp. | added 7/58; 4/61; eliminated 7/64 | |
| SSMX | Southwestern Sugar & Molasses Co. | 1/52-4/61 |
| National Molasses Co. | 7/65-1/75; eliminated 4/75 | |
| The David J. Joseph Co. | added 4/90; 1/94; eliminated 4/2000 | |
| Joseph Transportation Inc. | added 4/2000; 7/2000 | |
| SSOR | Sisseton Southern Ry. Co. | added 1/88; eliminated 10/89; 1/94-7/2000 |
| SSPB | Seaspan International Ltd. | 1/94-7/2000 |
| SSPX | A.E. Staley Manufacturing Co. | added 4/92; 1/94-7/2000 |
| SSSX | Transportation Logistics Corp. | added 7/94; eliminated 10/99; 7/2000 |
| SSVX | Spray Services, Inc. | added 7/77; eliminated 1/79 |
| SSI Industries, Inc. | added 1/79; 1/80; eliminated 5/83 | |
| SSI Industries, Inc. (MofW cars) | 1/94-7/2000 | |
| SSW | Cotton Belt Route | 23-Jul |
| St. Louis Southwestern Ry. Co. | 4/38-1/94; eliminated 10/97 | |
| Union Pacific R.R. Co. | added 10/97; 7/2000 | |
| SSWN | Southern Pacific Chicago St. Louis Connection | added 1/90 |
| SPCSL, Corp. | 1/94; eliminated 7/97 | |
| Union Pacific R.R. Co. | added 7/97; 7/2000 | |
| SSX | Southern States Phosphate and Fertilizer Co. | added 1/53 |
| S&T | Sheffield & Tionesta Ry. | 4/38-1/52 |
| ST | Springfield Terminal Ry. Co. (Vermont) | 1/75-1/80; eliminated 4/85 |
| Springfield Terminal Ry. Co. (MA) | added 4/85; eliminated 10/87 | |
| Springfield Terminal Ry. Co. (NH) | added 10/87 | |
| Springfield Terminal Ry. Co. | Jan-94 | |
| Springfield Terminal Ry. Co. (NH) | eliminated 10/97 | |
| ST Rail System | Jul-00 | |
| STAX | Stauffer Chemical Co. -- Northern California Branch | 4/38-1/52; eliminated 7/56 |
| Stauffer Chemical Co. (Western Branch) | added 7/56; 10/57-1/75 | |
| Stauffer Chemical Co. | 1/80; eliminated 4/90 | |
| Rhone-Poulenc Basic Chemicals Co. | added 4/90; 1/94; eliminated 7/96 | |
| OCI Chemical Corp. | added 7/96; 7/2000 | |
| STCX | Standard Transit Co. (General American Transportation Corp.) | Apr-38 |
| Sterling China Co. | Jan-80 | |
| Sterling China Co. (captive service) | 1/94-7/2000 | |
| STDX | Standard Fuels, Inc. | added 1/60; 4/61-10/66; eliminated 1/69 |
| Mobil Oil Corp. | added 1/69; 4/70; eliminated 7/70 | |
| STE | Stockton Terminal and Eastern R.R. | 1/75-7/2000 |
| STEX | Strick Division, Fruehauf Corp. | 7/65; eliminated 7/66 |
| Sterling Chemicals, Inc. | added 1/87; 1/94-7/2000 | |
| STGX | South Texas Grain Co., Inc. | added 7/91; 1/94; eliminated 10/97; 7/2000 |
| STHX | Stauffer Chemical Co. of Nevada | eliminated 7/56 |
| STIX | Stauffer Chemical Co. | 4/38-1/52; eliminated 7/56 |
| Surface Transportation International, Inc. | 1/80; eliminated 4/80 | |
| STJX | Stone Container (Canada) Inc. | Jul-00 |
| STL | Seatrain Lines, Inc. | 1/75-1/80 |
| Seatrain Lines, Inc., Container Division | eliminated 4/81 | |
| STLH | St. Lawrence & Hudson Ry. Co. Ltd. | Jul-00 |
| STLX | Stauffer Chemical Co. (Southern California Branch) | 4/38-1/52; eliminated 7/56 |
| A.E. Staley Manufacturing Co. | added 4/80; 1/94-7/2000 | |
| STMA | St. Maries River R.R. Co. | added 10/80; 1/94-7/2000 |
| STMX | A.E. Staley Manufacturing Co., Industrial Products Group | 1/94-7/2000 |
| STNX | Stauffer Chemical Co., Niagara Division | Jan-52 |
| Stauffer Chemical Co. | eliminated 7/56 | |
| STOX | American Car and Foundry Division, ACF Industries Inc. -- temporary expiring 1Apr71 | Apr-70 |
| ACF Industries, Inc., Amcar Division -- temporary expiring 1Apr75 | Jan-75 | |
| ACF Industries, Inc., Amcar Division -- temporary expiring 1Jan81 | Jan-80 | |
| ACF Industries, Inc., Amcar Division | 1/94-7/2000 | |
| ACF Industries, Inc. | added 1/2001 | |
| STPX | Strategic Transport Systems, Inc. | Jul-00 |
| STR | Shawnee Terminal Ry. Co., Inc. | eliminated 7/99; 7/2000 |
| STRC | Stuart Channel Transportation Ltd. | Jan-94 |
| STRT | The Stewartstown R.R. Co. | 1/75-7/2000 |
| STRX | St. Regis Paper Co. | added 1/83; eliminated 5/83 |
| A.E. Staley Manufacturing Co. | added 4/90; eliminated 1/94 | |
| Trinity Industries Leasing Co. | added 1/94-7/2000 | |
| STSX | A.E. Staley Manufacturing Co. | added 10/90; 1/94-7/2000 |
| STTX | Trailer Train Co. | added 10/58; 4/61-7/65 |
| Trailer Train Co. (FC flat cars equipped with hitches and bridge plates. Cars are leased to shipper under Plan IV schedule and are free of any mileage charge to handling roads, but mileage must be reported by car number) | 10/66-10/68; eliminated 4/70 | |
| Trailer Train Co. | Apr-70 | |
| Trailer Train Co. (no definition) | Jan-75 | |
| Trailer Train Co. | added 7/79 | |
| Trailer Train Co. (flat cars with fixed hitches and no bridge plates for assigned intermodal service between lift-on/lift-off terminals only) | Jan-80 | |
| Trailer Train Co. | eliminated 1/92 | |
| TTX Co. | added 1/92 | |
| TTX Co. (standard deck flat cars, equipped with collapsable hitches and sliding bridgeplates, capable of handling two 45' dry trailers with 36" kingpin spacing at either lift on/lift off or end loading facilities) | 1/94-7/2000 | |
| STUX | Suburban Fuel Tank Car Co. | added 7/70; 1/75 |
| Suburban Tank Car Co. | eliminated 1/79 | |
| Continental Tank Car Corp. | added 1/79; 1/80; eliminated 10/80 | |
| STWX | Shippers' Car Line Division of ACF Industries, Inc. | 7/65; eliminated 4/66 |
| Struthers Wells Corp. | 1/80; eliminated 4/89; 1/94 | |
| STX | M. Steffen & Co., Inc. | 1/52-4/61 |
| SUAB | Southern Alabama R.R. Co., Inc. | added 1/89; eliminated 10/91; 1/94-7/2000 |
| SUBX | Doxol Gas Supply, Inc. | eliminated 4/65 |
| North American Car Corp. | added 4/65; 7/65-1/75; eliminated 1/77 | |
| SUCX | Merchants Despatch Transportation Corp. | 10/57-4/70 |
| SULX | Sultran Ltd. | added 7/81; 1/94-7/2000 |
| SUN | Sunset Ry. Co. | 1/75-7/2000 |
| SUNX | Sun Oil Co. | 4/38-4/70; eliminated 7/70; eliminated 1/72 |
| Sun Oil Co. of Pennsylvania | added 1/72; 1/75; eliminated 4/78 | |
| Sun Petroleum Products Co., a Division of Sun Oil Co. of Pennsylvania | added 4/78; 1/80; eliminated 4/82 | |
| Sun Refining and Marketing Co. | added 4/82; 1/94-7/2000 | |
| SUPX | Transit Co., Ltd. | 4/38-1/52; eliminated 10/53 |
| Union Tank Car Co. | added 10/53; 10/57; eliminated 1/60 | |
| SUR | State University R.R. Co. | 1/75-1/80 |
| SUTX | Sumter Transport Co. | added 1/99; 7/2000 |
| SUX | The Standard Ultramarine Co. | Jan-52 |
| The Standard Ultramarine & Color Co. | 10/57-4/61; eliminated 1/65 | |
| Holland-Suco Color Co. | added 1/65; 7/65-10/66; eliminated 1/68 | |
| Holland-Suco Color Co., Division of Chemetron Corp. | added 1/68; 4/70; eliminated 4/71 | |
| SUYX | Sunray Oil Corp. | Jan-52 |
| SV | Greater Shenandoah Valley Development Co. d/b/a Shenandoah Valley R.R. | 1/94-7/2000 |
| SVCX | Schenectady Varnish Co. | 4/38-4/61 |
| Schenectady Chemicals, Inc. | 7/65-1/80; eliminated 10/80 | |
| SVIL | Saltville Ry. Co. | added 1/82; eliminated 4/88 |
| SVMX | Speas Manufacturing Co. | Apr-38 |
| Speas Co. | 1/52-7/65; eliminated 10/65; added 1/70; 4/70-1/75; eliminated 1/80 | |
| SVRR | Shamokin Valley R.R. Co. | added 4/89; 1/94-7/2000 |
| SVTX | Servtex Materials Co. | added 7/75 |
| SVX | Socony-Vacuum Oil Co., Inc. | 1/52; eliminated 7/55 |
| Socony Mobil Oil Co., Inc. | added 7/55 | |
| Socony Mobil Oil Co., Inc. Central Region | eliminated 10/57 | |
| S&W | New York, Susquehanna & Western R.R. | 4/38-10/57 |
| SW | Southwestern R.R. Co. Inc. | added 1/91; 1/94-7/2000 |
| SWCX | The Sherwin-Williams Co. of Canada, Ltd. | 4/38-4/61; eliminated 7/64 |
| Swift Chemical Co. | added 1/74; 1/75 | |
| Swift Agricultural Chemicals Corp. | 1/80; eliminated 7/80 | |
| Estech General Chemicals Corp. | added 7/80; eliminated 10/81 | |
| Estech, Inc. | added 10/81; eliminated 1/85 | |
| SWFX | Southwest Forest Industries, Inc. | added 4/75; 1/80; eliminated 1/85 |
| Southwest Forest Industries | added 1/85; eliminated 10/87 | |
| Stone Container Corp. | added 10/87; 1/94-7/2000 | |
| SWGR | Seagraves, Whiteface and Lubbock R.R. Co. | added 7/90; 1/94; eliminated 4/96; 7/2000 |
| SWGX | Scoular Welsh Grain Co. | added 1/71; 1/75-1/80; eliminated 4/85 |
| SWJX | Supplee-Wills-Jones Milk Co. | 4/38-1/52; eliminated 10/53 |
| SWKR | San Pedro & Southwestern Ry. Co. | added 1/93; 1/94-7/2000 |
| SWLX | Southwestern Tank Line Co. (Phillips Petroleum Co.) | Apr-38 |
| Essel Corp. | 10/57; eliminated 10/59 | |
| Essel Petroleum Corp. | added 10/57; added 10/59; 4/61-4/70 | |
| Essel Corp. | 1/75-1/80; eliminated 10/84 | |
| SWP | Southwest Pennsylvania R.R. Co. | Jul-00 |
| SWPX | Shawinigan Chemicals Ltd. | 4/38-10/66; eliminated 10/69 |
| Gulf Oil Canada Ltd., Shawinigan Chemicals Division | added 10/69; eliminated 1/70 | |
| Gulf Oil Canada, Ltd. | added 1/70; 4/70; eliminated 4/72 | |
| Southwestern Portland Cement Co. | added 10/91; eliminated 10/93; 1/94-7/2000 | |
| SWRX | The Shallow Water Refining Co. | Jan-52 |
| Richmond Rail Equipment Leasing Co. | added 7/77; 1/80-1/94; eliminated 4/96 | |
| Transportation Equipment, Inc. | added 4/96; 7/2000 | |
| SWTX | Swift Tank Line (General American Transportation Corp.) | Apr-38 |
| General American Transportation Corp. | 1/52-7/65 | |
| Swift Tank Line (General American Transportation Corp.) | Oct-66 | |
| General American Transportation Corp. | 4/70; eliminated 7/74 | |
| SWX | The Sherwin-Williams Co. | Apr-38 |
| SWYX | Stauffer Chemical Co. of Wyoming | added 4/81; eliminated 4/90 |
| Rhone-Poulenc of Wyoming Co. | added 4/90; 1/94; eliminated 7/96 | |
| OCI Chemical Wyoming Co. | added 7/96; 7/2000 | |
| SXSX | Ron Johnson & Associates | 1/94-7/2000 |
| SYLX | Sylvania Industrial Corp. | Apr-38 |
| American Viscose Corp., Sylvania Division | Jan-52 | |
| SYRX | Sucorn Syrups & Sugars Inc. | added 1/65; 7/65 |
| Suncorn Syrups & Sugars, Inc. | 10/66; eliminated 10/69 | |
| Minnesota Corn Processors, Inc. Fructose Division | added 4/94; eliminated 4/96 | |
| Minnesota Corn Processors Bulk Products Division | added 4/96; 7/2000 | |
| SYSX | United States Systems, Inc. | added 10/90; 1/94; eliminated 4/2000 |
| Winter Bird Corp. | added 4/2000; 7/2000 | |
| SZX | The Sloan and Zook Co. | Apr-38 |