A retired Illinois Central caboose near Cairo, Illinois.

By Mobilus In Mobili (https://www.flickr.com/photos/mobili/24165274899/) [CC BY-SA 2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons

A retired Illinois Central caboose near Cairo, Illinois.
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List of Reporting Marks - I

Note: Marks ending in U are for container owners; marks ending in X are not common carriers; marks ending in Z are for trailers without flanged wheels. All other marks are of common-carrier railroads.

IAIS - Iowa Interstate Railroad
IALU - Japan Line, Ltd
IANR - Iowa Northern Railway
IAPX - Liquid Air, Inc.; Air Liquide America Corporation
IASZ - Iowa Interstate Railroad
IAT - Iowa Terminal Railroad
IATR - Iowa Traction Railroad
IBCX - Indiana Boxcar Corporation
IBNU - Interpool Container Pty, Ltd.
IBPX - Merchants Despatch Transportation Corp.; IBP, Inc.; Trinity Industries Leasing Co. (Lessee: IBP, Inc.; Tyson Foods, Inc.)
IBT - International Bridge and Terminal Company
IBYU - Tuscola and Saginaw Bay Railway
IC - Illinois Central Railroad; Illinois Central Gulf Railroad; Canadian National Railway
ICCU - ICCU Containers, Inc.
ICCX - International Catalyst Corporation
ICE - Iowa, Chicago and Eastern Railroad
ICEU - Inter-Continental Equipment, Inc.
ICEZ - GATX Capital Corporation
ICG - Illinois Central Gulf Railroad; Illinois Central Railroad; Canadian National Railway
ICGU - Illinois Central Railroad; Canadian National Railway
ICGZ - Illinois Central Railroad; Canadian National Railway
ICHU - Ingetra, AG
ICIU - Intermodal Containers, Inc.
ICIX - ICI Americas, Inc.
ICIZ - Intermodal Containers, Inc.
ICLU - International Container Leasing
ICLX - Intercoastal Leasing, Inc.
ICLZ - International Chassis Leasing, Inc.
ICMU - Interox America
ICMX - Illinois Cereal Mills, Inc.
ICOU - Japan Line, Ltd.
ICPU - Intermodal Container Pool, Inc.
ICPZ - Intermodal Container Pool, Inc.
ICRK - Indian Creek Railroad
ICRU - Ingetra, AG
ICRX - Island Creek Coal Company; Island Creek Corporation
ICRZ - Illinois Central Railroad; Canadian National Railway
ICSU - Transamerica Leasing, Inc.
ICSZ - Transamerica Leasing, Inc.; Union Pacific Railroad
IDAC - Idaho Central Railroad; Boise Pacific Railroad
IDAX - Industria del Alcali, SA
IDCU - Ideal Container
IDOX - United States Department of Energy (Idaho Operations Office)
IDSZ - Industrial Distribution Service, Inc.
IEAU - Intermodal Equipment Associates
IELZ - Iran Express Lines
IESX - IESX Corporation; Alliant Energy
IFBX - Indiana Farm Bureau Cooperative Association, Inc.; GE Rail Services Corporation
IFCX - Interstate Foods Corporation
IFLU - Interflow
IFOX - Industrial Fuel Oil, Inc.
IFRX - Infinity Rail
IFSU - Interlink Freight Systems
IFWZ - Independent Freightway, Inc.
IGN - International-Great Northern
IGPX - Industrial Steam Products
IHAU - Ihora Chemical Industrial
IHB - Indiana Harbor Belt Railroad
IHCU -
IHRC - Indiana Hi-Rail Corporation
IHSX - Alberni Pacific Railway (Western Vancouver Island Heritage Society)
IICZ - Illinois Central Railroad; Canadian National Railway
IIIU - III Transportation
IIIZ - III Transportation
IILU - Independent Container Line
IILZ - Independent Container Line
IIRC - Indiana Interstate Railway
IIRZ - III Transportation
IKCU - Interpool
IKKU - ICCU Containers, Inc.
IKSU - Transamerica Leasing, Inc.
ILDX - General Electric (Lighting Business Group)
ILMU - Flow Line Transport
ILSX - Independent Locomotive Service
ILTU - International Liquid Transport Company, Bv
ILW - Illinois Western Railroad
IMCX - International Minerals and Chemical Corporation; IMC Global Operations
IMEX - Indiana and Michigan Electric Company
IMFX - General American Transportation Corporation
IMMX - Industrial Minera Mexico, SA
IMRL - Illinois and Missouri Rail Link; Iowa, Chicago and Eastern Railroad
IMRR - Illinois and Midland Railroad
IMSX - IMCO Services (a division of the Halliburton Company); International Mill Service
IMSZ - Intermodal Systems, Inc.
IMTX - Multifoods Transportation, Inc.; AG Processing, Inc.
IMXZ - Intermodal Express, Inc.
IN - Indiana Northeastern Railroad
INCU - Intercontinental Transport, B.V.
INCX - Inco Railway
INCZ - Intercontinental Transport, B.V.
INCZ - Intercontinental Transport, B.V.
INDU - Dorothea Marine Entreprise and Management
INDX - Indelpro, SA de CV
INFX - Infineum USA, Ltd.
INGX - Ingomar Packing Company; GE Rail Services Corporation
INKU - Interpool, Ltd.
INLX - Inland Steel Coal Company; Incoal Company
INOH - Indiana and Ohio Railroad
INOX - Indiana and Ohio Rail Corporation
INPR - Idaho Northern and Pacific Railroad
INRD - Indiana Railroad
INSU - Intersub Services
INSX - Independent Salt Company
INT - Interstate Railroad; Norfolk Southern
INTU - Interpool Container Pty, Ltd.
INYU - Infinity Transportation Logistics
INTZ - Interpool, Ltd.
IOCR - Indiana and Ohio Central Railroad
IOCX - Rail Enterprises, Inc.
IOLU - Textainer Equipment Management (US), Ltd.
IOPX - Iowa Power and Light Company; MidAmerican Energy Company
IORY - Indiana and Ohio Railway
IPBX - INNOPHOS,Inc
IPCU - Independent Container Line
IPCX - International Paper
IPEX - Indeck Power Equipment Company
IPLX - Illinois Power Company
IPOX - A and R Leasing, LLP
IPPX - Intermountain Power Agency
IPSX - Midwest Energy Services Company; General American Marks Company
IPWX - Interstate Power Company; Alliant Energy
IQIX - Industria Quimica Del letmo, SA de CV
IR - Illinois RailNet
IREX - IRECO, Inc.
IRLX - Western Railroad Supply, Inc.
IRMZ - III Transportation
IRN - Conrail
IRRC - Iowa Railroad
IRRS - International Rail Road Systems, Inc.
IRSZ - Interpool/Rail Services, Ltd.
IRTX - Inter-Rail Transport
ISCU - I.S.C. Chemicals, Ltd.
ISCX - ISC, Inc.
ISG - ISG Railways
ISIZ - Intermodal Services, Inc.
ISLU - Islandia, Ltd.
ISPX - Western Company of North America
ISR - Iowa Southern Railroad
ISRR - Indiana Southern Railroad
ISSR - ISS Rail, Inc.
ISSU - Iceland Steamship Company, Ltd.
ISU - Iowa Southern Utilities (Southern Industrial Railroad)
ISW - Indiana Southwestern Railway
ITAU - Italian Line
ITAX - Illinois Transit Assembly, Inc.
ITB - Island Tug and Barge
ITC - Illinois Terminal Railroad; Norfolk and Western Railroad; Norfolk Southern
ITCU - Intercontainer
ITCX - International Technologies Corporation
ITDX - SULCOM, Inc.
ITEU - Compagnia Italiana Investimenti Alternativi
ITFX - Infinity Transportation
ITGX - ITG, Inc.
ITIU - International Transchem, Inc.
ITIX - Intermodal Technologies, Inc.
ITKU - Intertank, Ltd.
ITLU - Itel Containers International Corporation
ITLX - GE Rail Services Corporation
ITRU - Itel Containers International Corporation
ITSU - Iberhansaetic Transport System
ITSZ - International Transportation Service, Inc.
ITTX - Trailer Train Company, TTX Company
ITXX - Tiaxcalteca de Industrias, SA de CV
IU - Indianapolis Union
IVCX - Invista S.A.R.L.
IVLU - Ivarans Rederei, A/S
IXEU - Interox Quimica, SA
IXWU - Interox Chemicals, Ltd.