| 1 | WP | Aloha Islandair, Inc. | ICAO: PRI, IATA Prefix: 347, Name changed to Hawaii Island Air. Inc d/b/a Island Air w.e.f. 11 May 2004. | USA | AVCODES |
| 2 | WP | Hawaii Island Air. Inc d/b/a Island Air | ICAO: MKU, Callsign: Moku, Ceased operations on 11 November 2017. Name changed from Aloha Islandair, Inc. w.e.f. 11 May 2004. | USA | AVCODES |
| 3 | WP | Compania Aeronaves Del Peru, S.A. | | PE | AVCODES |
| 4 | WP | Wasaya Airways L.P. | ICAO: WSG, Callsign: Wasaya, Designator WT recalled by IATA. IATA designator changed from WG*. Name changed from Wasaya Airways Ltd. | CDN | AVCODES |
| 5 | WP | Air Antwerp | ICAO: ATW, Callsign: Devil, Ceased operations on 12 June 2021. | B | AVCODES |
| 6 | WP | Western Pacific R.R. Co. | 7/1965-1/1980; eliminated 10/1987 | | NAKINA |
| 7 | WP | Union Pacific R.R. Co. | added 10/1987; 1/1994-7/2005 | | NAKINA |
| 8 | WP | Western Pacific R.R. Co. | 7/65-1/80; eliminated 10/87 | | NRHS |
| 9 | WP | Union Pacific R.R. Co. | added 10/87; 1/94-7/2000 | | NRHS |
| 10 | WP | UNION PACIFIC RAILROAD CO. [WESTERN PACIFIC RR] | | | PWRC |
| 11 | WP | Western Pacific Railroad (Union Pacific Railroad) | | | RSRV |
| 12 | WP | Western Pacific | | USA | TRAFFIC |
| 13 | WP&Y | WHITE PASS AND YUKON CORPORATION, LTD. | | | PWRC |
| 14 | WPA | Western Pacific Airservice | Callsign: Westpac, | SOL | AVCODES |
| 15 | WPA | Western Pacific Airservice | | | ICAO1 |
| 16 | WPAC | WESTPAC INTERNATIONAL LLC | | | SCAC4 |
| 17 | WPAE | W P PRODUCE CORP | | | SCAC4 |
| 18 | WPAI | WOLVERINE PACKING CO | | | SCAC4 |
| 19 | WPAK | WATERLINK PAKISTAN (PVT) LTD | | | SCAC4 |
| 20 | WPAO | WEST PAK AVOCADO INC | | | SCAC4 |
| 21 | WPAP | WHITE PIGEON AUTOTRANSPORT CORP | | | SCAC4 |
| 22 | WPAZ | WRIGHT PATTERSON AIR FORCE BASE | | | PWRC |
| 23 | WPC | Commandair C.A. | Callsign: Command Air, | YV | AVCODES |
| 24 | WPCA | WORLD PETROLEUM CORPORATION | | | SCAC4 |
| 25 | WPCB | WESTRON PUMPS COMPRESSORS & BLOWERS | | | SCAC4 |
| 26 | WPCL | WESTERN PETROLEUM CO INC | | | SCAC4 |
| 27 | WPCN | WORLDWIDE PROCUREMENT COMPANY INC | | | SCAC4 |
| 28 | WPCO | WITHUS TRANSPORTATION CORPORATION | | | SCAC4 |
| 29 | WPCT | WRIGHT, PC TRUCKING LLC | | | SCAC4 |
| 30 | WPCW | WENATCHEE PETROLEUM CO | | | SCAC4 |
| 31 | WPCX | Transportation Management, Inc. | 1/1975; added 4/1975; eliminated 7/1976 | | NAKINA |
| 32 | WPCX | Missouri Valley Walnut Co. | added 7/1976; 1/1980; eliminated 1/1982 | | NAKINA |
| 33 | WPCX | Transportation Management, Inc. | 1/75; added 4/75 | | NRHS |
| 34 | WPCX | Missouri Valley Walnut Co. | 1/80; eliminated 1/82 | | NRHS |
| 35 | WPCX | MISSOURI VALLEY WALNUT CO. (TRANSPORTATION MANAGEMENT, INC.) | | | PWRC |
| 36 | WPCY | WILLOW PUBLISHING COMPANY | | | SCAC4 |
| 37 | WPDI | W P D INC | | | SCAC4 |
| 38 | WPDQ | WOLVERINE PRODUCE INC | | | SCAC4 |
| 39 | WPDR | WEST PENN DIESEL AND | | | SCAC4 |
| 40 | WPE | WEST PITTSON-EXETER RAILROAD CO. | | | PWRC |
| 41 | WPEH | WALTON, PHIL ENTERPRISES HAULING LT | | | SCAC4 |
| 42 | WPEK | WESPAK FISHERIES LTD | | | SCAC4 |
| 43 | WPEL | WESTERN PACIFIC EXPRESS LLC | | | SCAC4 |
| 44 | WPEN | WPE TRANSPORT LLC | | | SCAC4 |
| 45 | WPES | WEST POINT ENTERPRISES | | | SCAC4 |
| 46 | WPET | WESTERN PETROLEUM INC | | | SCAC4 |
| 47 | WPEX | Wabash Power Equipment Co. | added 7/1990; 1/1994-7/2005; eliminated 10/2008 | | NAKINA |
| 48 | WPEX | Wabash Power Equipment Co. | added 7/90; 1/94-7/2000 | | NRHS |
| 49 | WPEX | WABASH POWER EQUIPMENT COMPANY | | | PWRC |
| 50 | WPEX | Wabash Power Equipment | | | RSRV |
| 51 | WPEX | WABASH POWER EQUIPMENT COMPANY | | | SCAC4 |
| 52 | WPGX | Western Paving Construction Co. | added 4/1974; 1/1975-1/1980; eliminated 1/1980; 1/1994-7/2005 (not listed) | | NAKINA |
| 53 | WPGX | Western Paving Construction Co. | added 4/74; 1/75-7/2000 | | NRHS |
| 54 | WPGX | WESTERN PAVING CONSTRUCTION CO. | | | PWRC |
| 55 | WPGX | Western Paving Construction | | | RSRV |
| 56 | WPGX | WESTERN PAVING CONSTRUCTION CO | | | SCAC4 |
| 57 | WPH | Wat Phnom Airlines | IATA: WD, Callsign: Wat Phnom, IATA Prefix: 913, Ceased operations during 2014. | K | AVCODES |
| 58 | WPHX | Waite Phillips Co. | 7/1923 | | NAKINA |
| 59 | WPHX | Wacker Polymers, LP | added 10/2008 | | NAKINA |
| 60 | WPHX | *WAITE PHILLIPS CO. | | | PWRC |
| 61 | WPHX | +WACKER POLYMERS, LP | | | PWRC |
| 62 | WPHX | WACKER POLYMERS LP | | | SCAC4 |
| 63 | WPIL | WPI LOGISTICS LLC | | | SCAC4 |
| 64 | WPIM | WALLER PETROLEUM INC | | | SCAC4 |
| 65 | WPIQ | WESTERN PRIDE INC | | | SCAC4 |
| 66 | WPIX | WHOLESALE POWER, INC. | | | PWRC |
| 67 | WPIX | WHOLESALE POWER INC | | | SCAC4 |
| 68 | WPIZ | WALPORT INC. | | | PWRC |
| 69 | WPK | Air-Lift Associates, Inc. | Callsign: Wolfpack, | USA | AVCODES |
| 70 | WPK | Air-Lift Associates | | | ICAO1 |
| 71 | WPK | | Real: KZK GOP, City: Katowice | PL | TRAFFIC |
| 72 | WPKGSG | WPK Gdansk-Sopot-Gdynia | | PL | TRAFFIC |
| 73 | WPKK | Wojewódzkie Przedsiębiorstwo Komunikacyjne w Katowicach | | PL | TRAFFIC |
| 74 | WPKL | WILHEIT PACKAGING LLC | | | SCAC4 |
| 75 | WPKSLU | Wojewódzkie Przedsiębiorstwo Komunikacyjne w Słupsku | City: Słupsk | PL | TRAFFIC |
| 76 | WPKT | WOLF PAK TRANSPORT LLC | | | SCAC4 |
| 77 | WPL | Aeronaves del Peru S.A. | Callsign: Peru, | PE | AVCODES |
| 78 | WPLN | WORLD PACIFIC LINE | | | SCAC4 |
| 79 | WPLT | WIRCO PRODUCTS LIMITED | | | SCAC4 |
| 80 | WPLX | White Provision Co., Inc. | 7/1932-7/1935 | | NAKINA |
| 81 | WPLX | North American Car Corp. | added 1/1967; 4/1970-1/1980; eliminated 1/1984 | | NAKINA |
| 82 | WPLX | General Electric Railcar Services Corp. | added 1/1984; 1/1994; eliminated 10/1994 | | NAKINA |
| 83 | WPLX | North American Car Corp. | added 1/67; 4/70-1/80 | | NRHS |
| 84 | WPLX | General Electric Railcar Services Corp. | 1/94; eliminated 10/94 | | NRHS |
| 85 | WPLX | WHITE PROVISION CO., INC. | | | PWRC |
| 86 | WPLX | (NATX) GENERAL ELECTRIC RAILCAR SERVICES CORPORATION | | | PWRC |
| 87 | WPLX | White Provision Co. (GE Rail Services) | | | RSRV |
| 88 | WPMC | WESTERN POLYMER CORP | | | SCAC4 |
| 89 | WPMI | WILLIS PERMIAN MOVERS INC | | | SCAC4 |
| 90 | WPMU | UNION PACIFIC RAILROAD COMPANY | | | PWRC |
| 91 | WPMU | Western Pacific Railroad (Union Pacific Railroad) | | | RSRV |
| 92 | WPMW | Western Pacific R.R. Co. | added 1/1984; eliminated 10/1987 | | NAKINA |
| 93 | WPMW | Union Pacific R.R. Co. | added 10/1987; 1/1994-7/2005 | | NAKINA |
| 94 | WPMW | Western Pacific R.R. Co. | eliminated 10/87 | | NRHS |
| 95 | WPMW | Union Pacific R.R. Co. | added 10/87; 1/94-7/2000 | | NRHS |
| 96 | WPMW | UNION PACIFIC RAILROAD CO. [WESTERN PACIFIC RR.] (MAINTENANCE OF WAY EQUIPMENT) | | | PWRC |
| 97 | WPMW | Western Pacific Railroad (Union Pacific Railroad) | | | RSRV |
| 98 | WPMW | WINNIPEG PATTERN & MODEL WORKS LTD | | | SCAC4 |
| 99 | WPNT | WALKERS POINT MARINA | | | SCAC4 |
| 100 | WPNX | Wilson Provision Co. (North American Car Corp.) | 7/1932-7/1935 | | NAKINA |
