| 1 | MWP | Monongahela West Penn Public Service Co. | 7/1935-1/1941 | | NAKINA |
| 2 | MWP | Monongahela West Penn Public Service Co. | Apr-38 | | NRHS |
| 3 | MWP | *MONONGAHELA WEST PENN PUBLIC SERVICE CO. | | | PWRC |
| 4 | MWP | *MIDWEST PROCESSING CO. | | | PWRC |
| 5 | MWPA | MATTHEWS PALLET | | | SCAC4 |
| 6 | MWPB | MIDWES | | | SCAC4 |
| 7 | MWPC | MIAMI WASTE PAPER CO INC | | | SCAC4 |
| 8 | MWPD | MISCELLANEOU | | | SCAC4 |
| 9 | MWPN | MOUNTAIN WEST PROPANE INC | | | SCAC4 |
| 10 | MWPO | MID-WEST TRAFFIC INC | | | SCAC4 |
| 11 | MWPQ | MATUSCHEK WELDING PRODUCTS INC | | | SCAC4 |
| 12 | MWPR | MID WEST PRECISION MOULD LTD | | | SCAC4 |
| 13 | MWPS | MERIDIAN WOOD PRODUCTS | | | SCAC4 |
| 14 | MWPT | MIDWEST PALLET CO | | | SCAC4 |
| 15 | MWPX | Murco Wall Products Inc. | 7/2005 (not listed) | | NAKINA |
| 16 | MWPX | Pasbro Holding Co. | added 7/1969; 4/1970-1/1975; eliminated 4/1978 | | NAKINA |
| 17 | MWPX | Pasbro Holding Co. | added 7/69; 4/70-1/75; eliminated 4/78 | | NRHS |
| 18 | MWPX | *PASBRO HOLDING CO. | | | PWRC |
| 19 | MWPX | +MURCO WALL PRODUCTS, INC. | | | PWRC |
| 20 | MWPX | Murco Wall Products | | | RSRV |
