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.

F

• FAIX - FAIX Leasing
• FALX - Falk Corporation
• FANU - Brenner Tank, Inc.
• FAPR - Floydada and Plainview Railroad
• FARX - Farmers Cooperative Company (of Cleghorn, Iowa)
• FBAU - Ahlers Lines NV
• FBDC - Ford County Historical Railroad Preservation Foundation
• FBFU - Marine Transworld Equipment Corporation
• FBMU - Cie Maritime Belge, SA
• FBMX - Fayblock Materials
• FBOX - Trailer Train Company, TTX Company
• FBSU - Franco Belgian Services
• FBZU - China Ocean Shipping Company
• FC - Fulton County Railroad
• FCCM - Compania de Ferrocarriles Chiapas Mayab, SA de CV
• FCCX - Farmers Cooperative Company, Finova Capital Corporation
• FCDN - Ferrocarril de Nacozari
• FCEN - Florida Central Railroad
• FCEX - Farmers Union Central Exchange
• FCIN - Frankfort and Cincinnati Railroad
• FCM - Ferrocarril Mexicano
• FCP - Ferrocarril del Pacifico
• FCR - Fulton County Railway
• FCRD - First Coast Railroad
• FCRK - Falls Creek Railroad
• FCTX - Farmers' Commodities Transportation
• FDDM - Fort Dodge, Des Moines and Southern Railway, Chicago and North Western Railway, Union Pacific Railroad
• FDMA - Ferrocarril de Minatitlan al Carmen
• FDSU - Foodsource, Inc.
• FDSZ - Foodsource, Inc.
• FEC - Florida East Coast Railway
• FECU - Yamashita-Shinnihon Line
• FECZ - Florida East Coast Railway
• FEIX - Farmers Elevator, Inc.
• FEMX - Freight Equipment Management Company
• FEPX - FirstEnergy Corp
• FEXZ - Florida Express Carriers, Inc.
• FFEZ - Frozen Food Express
• FFFZ - Flexi-Van Leasing, Inc.
• FFIX - Procor, Ltd.
• FFTX - Fun Trains, Inc. (operators of the Florida Fun Train)
• FGCX - Florida Gulf Coast Railroad Museum
• FGER - Fruit Growers Express
• FGEX - Fruit Growers Express
• FGGX - Farmers Grain Cooperative
• FGLK - Finger Lakes Railway
• FGLX - Factor Gas Liquids, Inc.
• FGMR - Fruit Growers Express
• FGTX - Florida Gas Terminals, Inc.
• FGWX - Federal Grain Inspection Service (USDA)
• FHRX - Flint Hills Resources
• FILX - Wellman, Inc.
• FIMX - Franklin Industrial Minerals
• FINU - Interpool, Ltd.
• FINX - Finley Company, Inc.; Trinity Rail Management; Total Petrochemicals USA
• FIR - Flats Industrial Railroad
• FISZ - Ecorail, Inc.
• FJG - Fonda, Johnstown and Gloversville Railroad
• FJLX - Big West Oil Company
• FL - Family Lines System
• FLAX - Flexsys America
• FLAZ - Flexi-Van Leasing
• FLCX - Flex Leasing Corporation
• FLDX - DTE Transportation Services, Inc.
• FLEX - RailLease, Inc.
• FLGZ - Flexi-Van Leasing
• FLIX - Farmland Industries, Inc.
• FLJX - Big West Oil Company
• FLNX - R. P. Flynn, Inc., Ohio Railway Supply
• FLOX - Flex Leasing Company
• FLRX - ADM Milling Company
• FLSX - Great Miami, Inc.
• FLT - Foss Launch and Tug
• FLTZ - Flexi-Van Leasing
• FLXU - Flexi-Van Leasing
• FLXZ - Flexi-Van Leasing
• FMCU - FMC Corporation (Industrial Chemical Group)
• FMGU - Flota Mercante Grancolombiana, SA
• FMID - Florida Midland Railroad
• FMIX - CCKX, Inc.
• FMLX - FMC Corporation (Inorganic Chemicals Division)
• FMOX - FMC Corporation (Inorganic Chemicals Division)
• FMRC - Farmrail Corporation
• FNAX - Ferrellgas LLP
• FNE - TFM, SA de CV
• FNM - Ferrocarriles Nacionales de Mexico
• FNOR - Florida Northern Railroad
• FOR - Fore River Railroad
• FORZ - Flexi-Van Leasing
• FP - Fordyce and Princeton Railroad
• FPAX - Formosa Plastics Corporation, Formosa Transrail Corporation
• FPBX - Federal Paper Board Company, International Paper Corporation
• FPCX - Occidental Chemical Corporation (PVC resins), Oxy Vinyls LP
• FPN - Ferrocarriles Nacionales de Mexico
• FPPX - Fayette Power Project
• FPXZ - Flexi-Van Leasing
• FRDN - Ferdinand Railroad, H and S Railroad
• FREU - ABS Industrial Verification, Inc.
• FRLU - Farrell Lines, Inc.
• FRR - Falls Road Railroad
• FRRX - Feather River Rail Society
• FRSU - China Ocean Shipping Company
• FRTX - Frit Transportation, Inc., Farm-City Transport, Inc.
• FRV - Fox River Valley Railroad; Wisconsin Central
• FRVR - Fox Valley and Western
• FSCX - Frank Mitacek Railway Service
• FSFL - Burlington Northern and Santa Fe Railway; BNSF Railway
• FSHX - GE Rail Services
• FSIX - FSIX, Inc.
• FSR - Fort Smith Railroad
• FSRR - Ferrosur
• FST - Ferrocarriles Nacionales de Mexico
• FSTU - Fastrac Intermodal, LLC
• FSTX - Fuel Supply Trust
• FSTZ - Fastrac Intermodal, LLC
• FSUD - Fort Street Union Depot Company
• FSVB - Fort Smith and Van Buren Railway
• FTCU - Firsttank Corporation
• FTCX - Far Port Cooperative, Inc.
• FTIX - FTIX Associates
• FTMZ - Fruit Growers Express
• FTSX - Fairmont Tamper
• FTTX - Trailer Train Company, TTX Company
• FUCU - Shinko Pantec Company, Ltd.
• FURX - First Union Rail
• FUS - Ferrocarriles Unidos del Sureste, Ferrocarriles Nacionales de Mexico
• FVIU - Flexi-Van, Inc.
• FVIZ - Flexi-Van Leasing
• FVLZ - Venezuelan Line
• FVPZ - Flexi-Van Leasing
• FVRR - Fredonia Valley Railroad
• FVW - Fox Valley and Western
• FWAZ - Flexi-Van Leasing
• FWCR - Florida West Coast Railroad
• FWD - Fort Worth and Denver Railway, Chicago, Burlington and Quincy Railroad, Burlington Northern Railroad, Burlington Northern and Santa Fe Railway
• FWDB - Fort Worth and Dallas Belt Railroad
• FWDR - Fort Worth and Dallas Railroad
• FWIU - Trans Ocean, Ltd.
• FWLX - Foster Wheeler Ltd.
• FWRY - Fillmore and Western Railway
• FWTX - American Railcar Leasing, LLC - SMBC Rail Services LLC^[1]
• FWTZ - Flexi-Van Leasing
• FWU - Fort Wayne Union
• FWWR - Fort Worth and Western Railroad
• FXE - Ferromex