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.

W

• WA - Western Railway of Alabama; Seaboard System Railroad; CSX Transportation
• WAB - Wabash Railroad; Norfolk Southern
• WACR - Washington County Railroad
• WACX - PCS Phosphate Company
• WAG - Wellsville, Addison and Galeton Railroad
• WAGX - PCS Phosphate Company
• WAL - Western Allegheny Railroad
• WAMX - Watco Transportation Services, L.L.C.
• WAR - Warrenton Railroad
• WAS - Waynesburg Southern
• WATC - Washington Terminal Company
• WATR - Waterville Railroad
• WAW - Conrail
• WBC - Wilkes-Barre Connecting Railroad
• WBCX - Williams Brothers Concrete
• WBMX - Wilkes-Barre Milling (Lauhoff Grain Company)
• WBTS - Waco, Beaumont, Trinity and Sabine Railway
• WC - Wisconsin Central Railway; Canadian National Railway
• WCCL - Wisconsin Central Railway; Canadian National Railway
• WCDX - Far-Mar-Co, Inc.
• WCE - West Coast Express
• WCHX - Walter Haffner Company
• WCRC - Washington Central Railroad
• WCRX - United Grain Corporation
• WCTR - WCTU Railway
• WCTX - West Central Cooperative
• WDRR - White Deer and Reading Railroad
• WDTX - Washington State Department of Transportation
• WE - Wheeling and Lake Erie Railway (current)
• WECX - Westinghouse Electric Corporation
• WEIX - Wilbur-Ellis Company
• WELX - Welland Chemical, Inc.
• WEPX - Wisconsin Electric Power Company
• WERZ - Werner Enterprises
• WESX - BC Timber, Ltd.
• WFAX - Western Fuels Association, Inc.
• WFCX - Western Farmers Electric Cooperative
• WFE - Western Fruit Express; Burlington Northern Railroad
• WFIX - WFIX Partners; Wells Fargo Rail
• WFRX - WFEC Railroad Company; Wells Fargo Rail
• WGBX - W. G. Block Company
• WGCR - Wiregrass Central Railroad
• WGRR - Williams and Grand Ronde Railroad
• WHCX - Western Hay Corporation
• WHI - Burlington Northern Railroad
• WHN - Conrail
• WHSX - GE Rail Services
• WICT - Wisconsin and Calumet Railroad
• WIF - West India Fruit and Steamship Company
• WIGX - Wigeon Car Company
• WISX - Wisconsin Power and Light
• WITX - Continental Carbon Company
• WIWR - Wisconsin Western Railroad
• WKRL - Western Kentucky Railway
• WLE - Wheeling and Lake Erie Railway (former)
• WLFB - Wolfeboro Railroad
• WLO - Waterloo Railway
• WLPX - West Lake Polymers
• WLRL - Washington-Lincoln Railink
• WM - Western Maryland Railroad; Baltimore and Ohio Railroad; Chessie System; CSX Transportation
• WMI - West Michigan Railroad
• WMSC - White Mountain Scenic Railroad
• WMSR - Western Maryland Scenic Railroad
• WMTZ - Wal-Mart Transportation
• WMWN - Weatherford, Mineral Wells and Northwestern Railway
• WN - Wisconsin Northern Railroad
• WNF - Winfield Railroad
• WNFR - Winnifrede Railroad
• WNGX - Western Natural Gas Company
• WNYP - Western New York and Pennsylvania Railroad
• WOD - Washington and Old Dominion Railroad
• WOPR - West Oakland Pacific Railroad
• WP - Western Pacific Railroad; Union Pacific Railroad
• WPGX - Western Paving Construction Company
• WPLX - GE Rail Services
• WPMW - Western Pacific Railroad (Maintenance of way)
• WPRR - Willamette and Pacific Railroad
• WPSX - Wisconsin Public Service Corporation
• WPY - White Pass and Yukon Route
• WRA - Western Railway of Alabama; Seaboard System Railroad; CSX Transportation
• WRDX - Iowa-Illinois Gas and Electric Company
• WREX - Western Refrigerator Express
• WRL - Western Refrigerator Line, Washington Royal Line
• WRLX - Relco Tank Line
• WRNX - Gulf Oil Products Company; Chevron USA, Inc.
• WRPX - Public Service Company of Indiana
• WRRC - Western Rail Road Company
• WRSX - Scholle Corporation
• WRTX - Western Rail Leasing Corporation
• WRWK - Providence and Worcester Railroad
• WRX - Western Refrigerator Line Company
• WS - Ware Shoals Railroad
• WSCX - Buffalo Brake Beam Company
• WSJR - Goderich-Exeter Railway
• WSOR - Wisconsin and Southern Railroad
• WSOX - Wisconsin and Southern Leasing Company
• WSR - Warren and Saline River Railroad
• WSRC - West Shore Railroad Corporation
• WSS - Winston-Salem Southbound Railway
• WSX - National Steel Corporation (Weirton Steel Division)
• WSYP - White Sulphur Springs and Yellowstone Park Railway
• WT - Weldwood Transportation, Ltd., Wyandotte Terminal Railroad
• WTA - Wichita Terminal Association
• WTCO - Watco Railways
• WTCX - Weyerhaeuser Company
• WTOH - Western Ohio Railroad
• WTRY - Wilmington Terminal Railroad
• WTSE - West Shore Railroad Corporation
• WTTX - Trailer Train Company
• WURR - Wallowa Union Railroad
• WUT - Wichita Union Terminal Railway
• WUTX - Washington Utilities and Transportation Commission (scale test cars)
• WVCX - Westvaco Corporation
• WVN - West Virginia Northern Railroad
• WVRR - Whitewater Valley Railroad
• WW - Winchester and Western Railroad
• WWR - Washington Western, Western Washington Railroad
• WWRC - Wilmington & Western Railroad
• WWLX - LaRoche Industries, Inc.
• WWPX - Willimantic Waste Paper, Inc.
• WWSX - Standard Car Truck Company
• WWUX - Unimin
• WYCX - Weyerhauser Canada, Ltd.
• WYS - Wyandotte Southern Railroad