| 1 | WM | Windward Islands Airways International N.V. | ICAO: WIA, Callsign: Windward, IATA Prefix: 295, | NA | AVCODES |
| 2 | WM | Western Maryland Ry. Co. | 8/1920-1/1980; eliminated 1/1984 | | NAKINA |
| 3 | WM | Baltimore & Ohio R.R. Co. | added 1/1984; eliminated 7/1987 | | NAKINA |
| 4 | WM | The Chesapeake and Ohio Ry. Co. | added 7/1987; eliminated 10/1987 | | NAKINA |
| 5 | WM | CSX Transportation, Inc. | added 10/1987; 1/1994-7/2005 | | NAKINA |
| 6 | WM | Western Maryland Ry. Co. | 4/38-1/80 | | NRHS |
| 7 | WM | Baltimore & Ohio R.R. Co. | eliminated 7/87 | | NRHS |
| 8 | WM | The Chesapeake and Ohio Ry. Co. | added 7/87; eliminated 10/87 | | NRHS |
| 9 | WM | CSX Transportation, Inc. | added 10/87; 1/94-7/2000 | | NRHS |
| 10 | WM | CSX TRANSPORTATION, INC. {CHESSIE SYSTEM; B&O; WESTERN MARYLAND RY] | | | PWRC |
| 11 | WM | Western Maryland Railroad (CSX Transportation) | | | RSRV |
| 12 | WM | WESTERN MARYLAND RAILWAY COMPANY (C | | | SCAC4 |
| 13 | WM | BDWM Transport AG, Wohlen - Meisterschwanden | | CH | TRAFFIC |
| 14 | WM | Wagonmarket, spol. s.r.o. | | SK | VKM |
| 15 | WM&N | Weatherford, Mineral Wells & Northwestern Ry. Co. | 7/1923-4/1938 | | NAKINA |
| 16 | WM&N | Weatherford, Mineral Wells & Northwestern Ry. Co. | Apr-38 | | NRHS |
| 17 | WM&N | WEATHERFORD, MINERAL WELLS & NORTHWESTERN RWY. CO. | | | PWRC |
| 18 | WMA | Watermakers Air | Callsign: Watermakers, | USA | AVCODES |
| 19 | WMAA | WERNER, MIKE TRUCKING INC | | | SCAC4 |
| 20 | WMAE | WARLAND, MARIANNE | | | SCAC4 |
| 21 | WMAF | WEISMAN ART FOUNDRY | | | SCAC4 |
| 22 | WMAG | WATER MAGIC | | | SCAC4 |
| 23 | WMAI | WESTBY, MARK & ASSOCIATES INC | | | SCAC4 |
| 24 | WMAJ | WESTERN MOUNTAIN TRANSPORT INC | | | SCAC4 |
| 25 | WMaJ | Vittsjö - Markaryd Järnväg | 1892 - 1897 | S | svenska-lok.se |
| 26 | WMAM | WILLIAM AMERICA | | | SCAC4 |
| 27 | WMATA | Washington Metropolitan Area Transit Authority | | USA | TRAFFIC |
| 28 | WMBC | WILMOT, BRUCE T | | | SCAC4 |
| 29 | WMBT | WMB TRANSPORTATION | | | SCAC1 |
| 30 | WMBT | WIDEMAN, B TRUCKING | | | SCAC4 |
| 31 | WMBU | WHITE MARTINS GASES INDUSTRIAIS LTD | | | SCAC4 |
| 32 | WMBX | Willbros Terminal Co. | added 10/1967; 4/1970; eliminated 7/1974 | | NAKINA |
| 33 | WMBX | North American Car Corp. | 1/1975; added 4/1975; eliminated 7/1976 | | NAKINA |
| 34 | WMBX | Willbros Terminal Co. | added 10/67; 4/70; eliminated 7/74 | | NRHS |
| 35 | WMBX | North American Car Corp. | 1/75; added 4/75; eliminated 7/76 | | NRHS |
| 36 | WMBX | (NATX) NATX (WILLBROS TERMINAL CO.) | | | PWRC |
| 37 | WMCD | WEST MICHIGAN CONSOLIDATORS | | | SCAC4 |
| 38 | WMCI | WEST MICHIGAN TRANSPORT LLC | | | SCAC4 |
| 39 | WMCL | WHITELAW MACHINERY COMPANY LIMITED | | | SCAC4 |
| 40 | WMCM | WIMCO METALS INC | | | SCAC4 |
| 41 | WMCO | WINGHAM COLONY FARMS | | | SCAC4 |
| 42 | WMCP | WILMAC ENTERPRISES LLC | | | SCAC4 |
| 43 | WMCQ | WHITEWATER MARINE CORP | | | SCAC4 |
| 44 | WMCR | WATKINS MANUFACTURING CORP | | | SCAC4 |
| 45 | WMCS | WINDMILL CABINET SHOP LTD | | | SCAC4 |
| 46 | WMCW | WOOIL MARINE CO LTD | | | SCAC4 |
| 47 | WMCX | The Westinghouse Machine Co. | 8/1920 | | NAKINA |
| 48 | WMCX | The Westinghouse Machine Co. (Westinghouse Electric & Manufacturing Co.—Machine Works) | 7/1923 | | NAKINA |
| 49 | WMCX | L.H. Wentz (Oil Division) | 7/1935 | | NAKINA |
| 50 | WMCX | Williams Molasses Co. | 4/1947-1/1950 | | NAKINA |
| 51 | WMCX | *WESTINGHOUSE ELECTRIC & MFG. CO, MACHINE WORKS [WESTINGHOUSE MACHINE CO.] | | | PWRC |
| 52 | WMCX | *WILLIAMS MOLASSES CO. | | | PWRC |
| 53 | WMCX | Westmoreland Coal Company | | USA | TRAFFIC |
| 54 | WMCY | WOEBER MUSTARD COMPANY | | | SCAC4 |
| 55 | WMCZ | WESTMORELAND COAL COMPANY | | | PWRC |
| 56 | WMED | WIERSMA, ED TRUCKING INC | | | SCAC4 |
| 57 | WMEI | WESTERN MERCHANDISE EXPRESS INC | | | SCAC4 |
| 58 | WMEP | W M E TRANSPORTATION | | | SCAC4 |
| 59 | WMER | WEIMER, L & S TRUCKING LTD | | | SCAC4 |
| 60 | WMES | WALSH MESSENGER SERVICE, INC | | | SCAC1 |
| 61 | WMES | WEST-METRO EXPRESS | | | SCAC4 |
| 62 | WMFA | WIN-MAR FREIGHT MANAGEMENT INC | | | SCAC4 |
| 63 | WMFI | WELTON MOTOR FREIGHT INC | | | SCAC4 |
| 64 | WMFS | WIN-MAR FREIGHT SYSTEMS | | | SCAC4 |
| 65 | WMFT | WHITE MARSH TRANSPORT INC | | | SCAC4 |
| 66 | WMGB | WILLIAMS, G & B ENTERPRISES LTD | | | SCAC4 |
| 67 | WMGO | WILMINGTON OIL CO INC | | | SCAC4 |
| 68 | WMGP | WELMAR GROUP, THE | | | SCAC4 |
| 69 | WMGT | WORLD MANAGEMENT INC | | | SCAC4 |
| 70 | WMGU | WAXING MOON GLOBAL LIMITED | | BVI | BIC |
| 71 | WMGX | Wentz & McCasky Gasoline Co. | 7/1923 | | NAKINA |
| 72 | WMGX | L.H. Wentz Oil Division | 7/1930-1/1941 | | NAKINA |
| 73 | WMGX | W.H. Schoenwald | 1/1943 | | NAKINA |
| 74 | WMGX | L.H. Wentz (Oil Division) | Apr-38 | | NRHS |
| 75 | WMGX | W. H. SCHOENWALD [L. H. WENTZ, OIL DIV.; WENTZ & MCCASKY GASOLINE CO.] | | | PWRC |
| 76 | WMHA | WHITLEY MOBILE HOMES INC | | | SCAC4 |
| 77 | WMHB | WALLACE MOBILE HOME SERVICE | | | SCAC4 |
| 78 | WMHN | WALTON MILK HAULING INC | | | SCAC4 |
| 79 | WMHR | WANNEMA | | | SCAC4 |
| 80 | WMI | West Michigan R.R. Co. | 7/2000-7/2005 | | NAKINA |
| 81 | WMI | West Michigan R.R. Co. | Jul-00 | | NRHS |
| 82 | WMI | WEST MICHIGAN RAILROAD CO. | | | PWRC |
| 83 | WMI | West Michigan Railroad Co | | | RSRV |
| 84 | WMI | WEST MICHIGAN RAILROAD CO | | | SCAC4 |
| 85 | WMIA | WESTPIER MARINE & INDUSTRIAL SUPPLY | | | SCAC4 |
| 86 | WMIC | WEST MICHIGAN CARTAGE INC | | | SCAC4 |
| 87 | WMIF | WASTE MANAGEMENT INC OF FLORIDA | | | SCAC4 |
| 88 | WMIQ | W MARINE INC | | | SCAC4 |
| 89 | WMIX | Waste Management of Illinois, Inc. | added 10/1996; eliminated 4/2000; 7/2000-7/2005 (not listed) | | NAKINA |
| 90 | WMIX | Waste Management of Illinois, Inc. | added 10/96; eliminated 4/2000; 7/2000 | | NRHS |
| 91 | WMIX | WASTE MANAGEMENT OF ILLINOIS, INC. | | | PWRC |
| 92 | WMIX | Waste Management of Illinois | | | RSRV |
| 93 | WMIZ | WIMPEY MINERAL | | | PWRC |
| 94 | WMJS | WMJ EXPRESS INC | | | SCAC4 |
| 95 | WMKA | WARMKA TRANSPORT INC | | | SCAC4 |
| 96 | WMKC | WM TRUCKING LLC | | | SCAC4 |
| 97 | WMKG | WILLIAMS TRUCKING | | | SCAC4 |
| 98 | WMKL | WILLIAMS TRUCKING LLC | | | SCAC4 |
| 99 | WMKN | WILLIAMS TRUCKING LC | | | SCAC4 |
| 100 | WMKR | W M TRUCKING INC | | | SCAC4 |
