| KABX | Kaber Co. | 1/75; added 4/75; 1/80; eliminated 7/93 |
| Bay State Milling Co. | eliminated 10/93 | |
| Kaber Co. | Jan-94 | |
| Canadian Resource Distribution Inc. | Jul-00 | |
| KACX | Kaiser Aluminum & Chemical Corp. | 4/61-1/94; eliminated 7/94; 7/2000 |
| KAIX | Rinker Materials Corp. | added 1/89; 1/94-7/2000 |
| KAMX | Kamen, Inc. | added 4/85; 1/94-7/2000 |
| KAPX | K.A. Powell (Canada) Ltd. | added 10/53; 10/57; eliminated 7/58 |
| KARX | Hamilton Elevators | added 10/80; eliminated 10/89 |
| General Electric Railcar Services Corp. | 1/94; eliminated 10/94 | |
| KATX | Marubeni America Corp. | eliminated 10/87 |
| KBEC | Kent, Barry, Eaton Connecting Ry., Inc. | added 4/80 |
| KBKX | Carey, Baxter and Kennedy, Inc. | 1/52-4/61 |
| KBSR | Kankakee, Beaverville and Southern R.R. Co. | added 4/78; 1/80-7/2000 |
| KC | The Kanawha Central Ry. Co. | Jan-75 |
| KCAX | KCAC, Inc. | eliminated 1/87 |
| KCC | Kansas City Connecting R.R. Co. | 1/75-1/80 |
| KCCX | Kimberly-Clark Co. | 4/38-4/61 |
| Kennecott Copper Corp. | added 4/70; 4/70-1/80; eliminated 4/81 | |
| Kennecott Corp. | added 4/81; eliminated 4/91 | |
| Kennecott Utah Copper Corp. | added 4/91; 1/94-7/2000 | |
| KCDX | Eastman Kodak Co. | 1/80-7/2000 |
| KCGX | Kaiser Cement & Gypsum Corp. | added 10/65; 10/66-1/75; eliminated 1/80 |
| Kaiser Cement Corp. | added 1/80; 1/80; eliminated 1/90 | |
| Mitsubishi Cement Corp. | added 1/90; 1/94; eliminated 1/97 | |
| Southdown, Inc. | added 1/97; eliminated 7/97; 7/2000 | |
| KCIX | Koppers Co., Inc. | added 1/65; 7/65; eliminated 4/66 |
| Sinclair-Koppers Co. | added 4/66; 10/66-4/70 | |
| ARCO/Polymers, Inc. | Jan-75 | |
| ARCO Polymers, Inc. | 1/80; eliminated 10/82 | |
| ARCO Chemical Co. | added 10/82; 1/94; eliminated 4/97 | |
| Nova Chemicals Inc. | added 4/97; 7/2000; eliminated 7/2000 | |
| KCLX | Kansas City Power & Light Co. | added 4/71; 1/75-1/94; eliminated 7/97; 7/2000 |
| KCMO | Kansas City, Mexico & Orient | 1/75-1/80 |
| KCMX | Kidd Creek Mines, Ltd. | added 4/82; eliminated 7/86 |
| Saskterra Fertilizers Ltd. | added 7/86; eliminated 10/90 | |
| Potash Corp. of Saskatchewan, Inc. | added 10/90; eliminated 1/91 | |
| Saskterra Fertilizers Ltd. | added 1/91; eliminated 4/91 | |
| PLM International, Inc. | added 4/91; 1/94 | |
| KCNW | Kelley's Creek & Northwestern R.R. Co. | 1/75-1/94 |
| KCPX | Kemira Chemicals Canada Inc. | added 7/99; 7/2000 |
| KCRX | Kootenay Central Rail Services Ltd. | Jul-00 |
| KCS | Kansas City Southern Ry. Co. | 7/65-7/2000 |
| KCT | Kansas City Terminal Ry. Co. | 4/38-1/75; eliminated 1/86; 1/94; eliminated 1/95 |
| KCTV | KCT Ry. Corp. | added 7/90; eliminated 7/92; 1/94-7/2000 |
| KCWB | Kansas City Westport Belt | 1/75-1/80 |
| KCWX | Kimberly-Clark of Canada Ltd. | added 7/77; 1/80; eliminated 1/94; 7/2000 |
| KCX | Kingsford Chemical Co. | eliminated 10/57 |
| Kingsford Co. | added 10/57; 10/57-4/61; eliminated 1/62 | |
| KDCX | Kodak Canada, Inc. | added 10/90; 1/94; eliminated 1/95 |
| Eastman Chemical Canada, Inc. | added 1/95; 7/2000 | |
| KDEX | KDEX Leasing Co. | added 10/86; eliminated 1/88 |
| Consolidated Transportation Corp. | eliminated 1/89 | |
| Jansen Rail Car, Inc. | added 4/89; 1/94; eliminated 1/96 | |
| GLNX Corp. | added 1/96; eliminated 4/2000; 7/2000 | |
| KDTX | Tomco Railway Car Co., Inc. | 7/65-1/80; eliminated 4/80 |
| KE | Kansas Eastern R.R. Inc. | Jul-00 |
| KEBX | Manufacturers Leasing Corp. | added 4/62; 7/65-1/80; eliminated 4/84 |
| KEBX | Ronald L. Boothman Remainder Trust | added 4/84; 1/94-7/2000 |
| KECX | Kuner-Empson Co. | 4/38-1/52 |
| KELX | Kellogg Company | added 7/81; 1/94-7/2000 |
| KENN | Kennecott Co. R.R. | 1/80-7/2000 |
| KENX | KENX Associates | added 4/78; 1/80 |
| KEYX | Keywell Corp. | 1/94-7/2000 |
| KFGX | Knauf Fiber Glass, GmbH | added 4/78; 1/80; eliminated 7/87; 1/94-7/2000 |
| KFMX | Oils Unlimited | 1/75-7/2000 |
| KFPX | Koppers Co., Inc. | added 10/69; 4/70-1/80; eliminated 10/87 |
| KFRX | Chicago Freight Car Leasing Co. | added 1/70; 4/70-1/75; eliminated 1/83 |
| KGB | Kewaunee, Green Bay & Western R.R. Co. | 4/38-10/66 |
| KGCX | Koppers Co., Inc. | added 4/55; 10/57-1/80; eliminated 10/89 |
| INDSPEC Chemical Corp. | added 10/89; 1/94; eliminated 1/98; 7/2000 | |
| KGFX | The Kingsford Co. | added 4/80; 1/94-7/2000 |
| KGLX | Commonwealth Edison Co. | added 10/99; 7/2000 |
| KGNX | General American Transportation Corp. | 1/52-7/65 |
| Hygrade Food Products Corp. (General American Transportation Corp.) | Oct-66 | |
| General American Transportation Corp. | 4/70; eliminated 1/72 | |
| KGRX | Kasgro Rail Corp. | added 10/96; 7/2000 |
| KHCX | Chief Petty Paper | added 10/88; eliminated 1/91 |
| KIIX | Kerley Industries, Inc. | added 10/84; eliminated 7/89 |
| Koppers Industries, Inc. | added 7/97; 7/2000 | |
| KIPX | Kentucky Independent Packing Co., Inc. (National Car Co.) | Apr-38 |
| KIT | Kentucky & Indiana Terminal R.R. Co. | 1/75-1/80; eliminated 4/82 |
| KJR | Berkman Rail Services, Inc. d/b/a Kiski Junction R.R. | added 10/95; eliminated 7/98; 7/2000 |
| KJRY | Keokuk Northern Real Estate Co. (d/b/a Keokuk Junction Ry.) | added 1/82; eliminated 4/82 |
| Keokuk Junction Ry. | added 4/82; 1/94-7/2000 | |
| KKCX | Keokuk Canning Co. | Apr-38 |
| KKRR | Knox & Kane R.R. Co. | added 10/82; 1/94-7/2000 |
| KLGX | Alan Kelling/KLGX | added 10/87; eliminated 1/89 |
| KLAX | H. Earl Clack Co. | 4/38-1/52 |
| KLSC | Kalamazoo, Lake Shore & Chicago Ry. | 1/94-7/2000 |
| KLSX | Kerford Limestone Co. | added 7/80; eliminated 10/84 |
| KM | The Kansas and Missouri Ry. and Terminal Co. | 1/75-1/80; eliminated 10/84 |
| The Kansas City Southern Ry. Co. | added 10/84 | |
| Kansas and Missouri Ry. and Terminal Co. | 1/94-7/2000 | |
| KMBX | Keilman Brothers | Oct-57 |
| KNC | Kingcome Navigation | Jan-75 |
| KMCX | Knappen Milling Co. | added 7/64; 7/65-10/66; eliminated 7/68 |
| Kerr-McGee Chemical Corp. | reporting marks changed from APMX 1/71; eliminated 11/73; 1/80; eliminated 4/93; added 10/93; 1/94; eliminated 1/95 | |
| Kerr-McGee Coal Corp. | added 1/95; eliminated 7/98; 7/2000 | |
| KMFX | Kaolin Mushroom Farms, Inc. | added 1/74; 1/75 |
| KMGX | Twin Mountain Rock Co. | added 7/91; 1/94; eliminated 1/97 |
| KMUX | Kershaw Manufacting Co. | 1/94-7/2000 |
| KNC | Kingcome Navigation | 1/80-7/2000 |
| KNDX | K & D Salvage Co. | added 1/73; 1/75; eliminated 4/76 |
| Golden State Metals, Inc. | added 4/76; 1/80; eliminated 4/89 | |
| KND Rail Services, Inc. | added 1/97; 7/2000; eliminated 7/2001 | |
| KNOR | Klamath Northern Ry. Co. | 1/75-1/80 |
| KNOX | Knox Metals Corp. | added 1/96; eliminated 4/97; 7/2000 |
| Philip Metals, Inc. | added 4/2001 | |
| KOAX | Coca-Cola U.S.A., a Division of The Coca-Cola Co. | added 4/71; 1/75-1/80 |
| Coca-Cola U.S.A. | eliminated 10/87 | |
| KOG | Texas and Pacific Railway Co. | 1/75; eliminated 1/77 |
| Missouri Pacific Railroad Co. | added 1/77; 1/80 | |
| Missouri Pacific System | eliminated 1/80 | |
| KOHX | Kohrs Packing Co. (cars no. 2601-2621) (National Car Co.) | Apr-38 |
| Kohrs Packing Co. (cars no. 3100-3150) (Mather Stock Car Co.) | Apr-38 | |
| KOPX | Koppers Co., Inc. | 4/38-1/52 |
| KOPX | National Equipment Leasing Corp. | added 4/62; 7/65-1/75; eliminated 4/75; 1/80 |
| KOTX | The Kanotex Refining Co. | 4/38-1/52; eliminated 10/53 |
| Anderson-Pritchard Oil Corp. | added 10/53 | |
| KPCX | Koppers Co., Inc. | 4/38-1/80; eliminated 10/89 |
| Koppers Industries, Inc. | added 10/89; 1/94-7/2000 | |
| KPGX | Kentucky Processing Co. | added 1/97; eliminated 1/99; 7/2000 |
| KPLX | Koppel, Inc. | 1/80; eliminated 1/85 |
| Agrex, Inc. | added 1/85; eliminated 1/88 | |
| Western Resources, Inc. | Jul-00 | |
| KPRX | Western Light & Telephone Co., Inc. | 1/52-4/61 |
| KPX | Kaw Paving Co. | 1/52-4/61 |
| KPXX | Electric Fuels Corp. | added 7/94; eliminated 7/96 |
| Progress Rail Services Corp. | added 7/96; 7/2000 | |
| KRCX | Keefe Packing Co. (Merchants Despatch Transportation Corp.) | Apr-38 |
| KRDX | K.R. D-X Co. | added 7/67; 4/70-1/80; eliminated 4/88 |
| KRFX | Kraft Foods, a Division of National Dairy Products Corp. | added 7/58; eliminated 4/61; eliminated 1/62 |
| KRIX | Kyle Rys., Inc. | added 4/96; eliminated 10/98 |
| General Electric Railcar Services Corp. | added 10/98; eliminated 1/2000 | |
| General Electric Rail Services Corp. | added 1/2000; 7/2000 | |
| KRL | Kasgro Rail Lines | added 10/2000 |
| KRLX | Kingan Refrigerator Line | Apr-38 |
| KRMX | Kerr-McGee Oil Industries, Inc. | added 7/56; 10/57-4/61 |
| Union Tank Car Co. | 7/65-4/70; eliminated 7/73 | |
| KRPX | Associated Electric Cooperative, Inc. | Jan-80 |
| Associated Electric Cooperative, Inc. (captive service) | Jan-94 | |
| KRR | Kiamichi R.R. Co., Inc. | added 1/88; 1/94; eliminated 10/96 |
| Kiamichi R.R. Co., L.L.C. | added 10/96; 7/2000 | |
| KRTX | Kendall Refining Co. | Apr-38 |
| KRWX | kalamazoo Rendering Works | 1/52; eliminated 4/55 |
| kalamazoo Rendering Works, Inc. | added 4/55; 10/57; eliminated 10/59 | |
| KSCX | Kaiser Steel Corp. | 1/52; added 7/66; 10/66-1/75; eliminated 7/78 |
| KSHX | State Highway Commission of Kansas | Apr-38 |
| KSMX | Kosmos Portland Cement Co. | 1/52-4/70; eliminated 4/72 |
| The Flintkote Co., Diamond Kosmos Cement Division | added 4/72; 1/75; eliminated 4/76 | |
| The Flintkote Co., Eastern Cement Region | added 4/76; eliminated 4/78 | |
| The Flintkote Co./Kosmos Cement Division | added 4/78; 1/80; eliminated 4/81 | |
| Kosmos Cement Co., Inc. | added 4/81; eliminated 1/89 | |
| KSW | Kansas Southwestern Ry. | added 4/92; 1/94-7/2000; eliminated 4/2001 |
| Central Kansas Ry., Inc. | added 4/2001 | |
| KT | Kentucky & Tennessee Ry. Co. | 4/38-1/80; eliminated 10/93; 1/94-7/2000 |
| KTCX | Klamath Gas Co. | added 7/63; 7/65-1/75; eliminated 1/80 |
| KTER | Kingston Terminal R.R. Corp. | added 7/80; eliminated 10/80 |
| KTIX | Korf Transport Corp. | added 7/75 |
| Georgetown Steel Corp. | 1/80; eliminated 1/81 | |
| KTTX | Trailer Train Co. | Jul-65 |
| Trailer Train Co. (FA flat cars equipped with tri-level automobile carrying superstructures with movable end sections of second, or second and third decks, furnished by member railroads. Cars are not equipped with hitches or bridge plates) | 10/66-10/68 | |
| Trailer Train Co. | Apr-70 | |
| Trailer Train Co. (flat cars, equipped with hinged end tri-level auto racks furnished by participant railroads) | 1/75-1/80 | |
| Trailer Train Co. | eliminated 1/92 | |
| TTX Co. | added 1/92 | |
| TTX Co. (standard deck flat cars with non-collapsable hitches, capable of handling any two trailers, with 36' kingpin spacing, whose overall combined length does not exceed 90' -- i.e., 2-45', 1-42' & 1-48', 1-40' & 1-48', etc. -- between lift on/lift off facilities only) | 1/94-7/2000 | |
| KTX | Keith Tank Line (Keith Ry. Equipment Co.) | Apr-38 |
| Keith Ry. Equipment Co. | 1/52-4/61 | |
| Shippers' Car Line Division of ACF Industries, Inc. | 7/65-1/75; eliminated 7/78 | |
| Shippers' Car Line Division, ACF Industries Inc. | added 10/78; 1/80; eliminated 4/88 | |
| ACF Industries, Inc. | added 4/88; 1/94; eliminated 7/97; 7/2000 | |
| KUCX | Kentucky Utilities Co. | added 7/76; 1/80; eliminated 4/91; added 10/92; 1/94-7/2000 |
| KVPX | KVP Co., Ltd. | 1/52-10/66; eliminated 4/67 |
| Brown Forest Industries Ltd., a Division of Brown Co. | added 4/67; eliminated 1/69 (reporting marks changed to BFIX) | |
| KVW | Kansas City, Kaw Valley & Western R.R. | 4/38-10/57 |
| Kansas City, Kaw Valley R.R. Inc. | Apr-61 | |
| KWT | K.W.T. Ry., Inc. | added 7/87; 1/94-7/2000 |
| KWTR | Keota Washington Transportation Co. | added 1/82 |
| KWTX | K&W Trucking Co., Inc. | Jan-94 |
| KWUX | Allis-Chalmers Power Systems, Inc. | 1/80; eliminated 1/83 |
| Utility Power Corp. | added 1/83; eliminated 10/90 | |
| Siemens Power Corp. | added 10/90; 1/94-7/2000; eliminated 4/2001 | |
| Siemens Westinghouse Power Corp. | added 4/2001 | |
| KXHR | Knoxville & Holston River R.R. Co., Inc. | added 10/98; 7/2000 |
| KYCX | Kirby Refining Co. | eliminated 7/56 |
| KYLE | Kyle R.R. Co. | added 4/82; added 1/86; 1/94-7/2000 |
| KYRX | Louisville Scrap Material Co., Inc. | added 10/96; eliminated 4/99 |
| Louisville Scrap Material | added 4/99; eliminated 10/99 | |
| Progress Rail Services Corp. | added 10/99; 7/2000 |