| KMKubina Metals | Grindstone, PA | Primary Metal Manufacturing331410 | — | ◐ LIKELY ACTIVE |
| LILabchem INC | Zelienople, PA | Chemical Manufacturing325998 | — | ◐ LIKELY ACTIVE |
| LMLagonda Machine INC | Washington, PA | Fabricated Metal Product Manufacturing332710 | 20–99 | ◐ LIKELY ACTIVE |
| LMLane Metal Prod | Pulaski, PA | Fabricated Metal Product Manufacturing332996 | — | ◐ LIKELY ACTIVE |
| LCLanxess CORP | Burgettstown, PA | Chemical Manufacturing325180 | — | ◐ LIKELY ACTIVE |
| LILectromat INC | Mars, PA | Electrical Equipment, Appliance & Component Manufacturing335932 | — | ◐ LIKELY ACTIVE |
| LPLesleh Precision INC | Rostraver Township, PA | Fabricated Metal Product Manufacturing332710 | — | ◐ LIKELY ACTIVE |
| LSLigonier Stone & Lime Concrete | Latrobe, PA | Nonmetallic Mineral Product Manufacturing327320 | 1–19 | ◐ LIKELY ACTIVE |
| LPLindy Paving Inc/zelienople Plt | Zelienople, PA | Petroleum and Coal Products Manufacturing324121 | — | ◐ LIKELY ACTIVE |
| LPLindy Paving - Plant 991 (second Ave) | Pittsburgh, PA | Petroleum and Coal Products Manufacturing324121 | — | ◐ LIKELY ACTIVE |
| LSLtv Steel Coompany INC Aliquippa Works | Aliquippa, PA | Chemical Manufacturing325300 | — | ◐ LIKELY ACTIVE |
Luxfer Magtech Saxonburg Plt | Saxonburg, PA | Chemical Manufacturing325180 | — | ◐ LIKELY ACTIVE |
| LMLuxfer MEL Technologies - Saxonburg | Saxonburg, PA | Primary Metal Manufacturing331491 | 20–99 | ◐ LIKELY ACTIVE |
| MPMagee Plastics Company | Warrendale, PA | Plastics and Rubber Products Manufacturing326130 | 20–99 | ◐ LIKELY ACTIVE |
| MFMarburger Farm Dairy INC. | Evans City, PA | Food Manufacturing311511 | 100–499 | ◐ LIKELY ACTIVE |
| MWMaxwell Welding & Machine | Burgettstown, PA | Fabricated Metal Product Manufacturing332312 | 20–99 | ◐ LIKELY ACTIVE |
| MIMcc International, INC. | Mc Donald, PA | Primary Metal Manufacturing331513 | 20–99 | ◐ LIKELY ACTIVE |
| MIMcc Intl/miller Cent Cast Inc/mcdonald Plt | Cecil, PA | Primary Metal Manufacturing331523 | — | ◐ LIKELY ACTIVE |
| MIMedart, INC. | Ellwood City, PA | Machinery Manufacturing333519 | 20–99 | ◐ LIKELY ACTIVE |
| MCMenasha Corp/yukon | Yukon, PA | Paper Manufacturing322230 | — | ◐ LIKELY ACTIVE |
| MPMenasha Packaging Company - Yukon | Ruffs Dale, PA | Paper Manufacturing322211 | 100–499 | ◐ LIKELY ACTIVE |
| MLMercer Lime & Stone CO | Slippery Rock, PA | Nonmetallic Mineral Product Manufacturing327410 | — | ◐ LIKELY ACTIVE |
| MLMesser LLC Braddock Plt | Braddock, PA | Chemical Manufacturing325120 | — | ◐ LIKELY ACTIVE |
| MFMetal Finishing Industries, INC. | Greensburg, PA | Fabricated Metal Product Manufacturing332813 | — | ◐ LIKELY ACTIVE |
| MIMinteq Intl Mfg | Slippery Rock, PA | Nonmetallic Mineral Product Manufacturing327120 | — | ◐ LIKELY ACTIVE |
| MMM & M Lime CO | Worthington, PA | Nonmetallic Mineral Product Manufacturing327410 | — | ◐ LIKELY ACTIVE |
| MGModerne Glass CO INC | Aliquippa, PA | Nonmetallic Mineral Product Manufacturing327215 | — | ◐ LIKELY ACTIVE |
| MCMoody Corporation | Zelienople, PA | Fabricated Metal Product Manufacturing332710 | 20–99 | ◐ LIKELY ACTIVE |
| MSMsa Safety Pittsburgh Mfg Llc/murrysville Plt | Murrysville, PA | Chemical Manufacturing325410 | — | ◐ LIKELY ACTIVE |
| NPNamsco Plastics Ind. Inc | New Kensington, PA | Plastics and Rubber Products Manufacturing326112 | 20–99 | ◐ LIKELY ACTIVE |
| NBNature's Blend | Ford City, PA | Furniture and Related Product Manufacturing337110 | 20–99 | ◐ LIKELY ACTIVE |
| NCNew Castle Union Station Craft Distillery | New Castle, PA | Beverage and Tobacco Product Manufacturing312140 | — | ◐ LIKELY ACTIVE |
| OPOberg - Precision Machining Center | Sarver, PA | Miscellaneous Manufacturing339112 | 100–499 | ◐ LIKELY ACTIVE |
| OSOesterlings Sandblasting/butler | Butler, PA | Fabricated Metal Product Manufacturing332312 | — | ◐ LIKELY ACTIVE |
| OPOhiopyle Prints, INC. | Ohiopyle, PA | Printing and Related Support Activities323113 | 100–499 | ◐ LIKELY ACTIVE |
| OIOpco Inc/latrobe | Latrobe, PA | Plastics and Rubber Products Manufacturing326140 | — | ◐ LIKELY ACTIVE |
| OUOpta USA Inc/affival INC | New Kensington, PA | Primary Metal Manufacturing331110 | — | ◐ LIKELY ACTIVE |
| OOrrco | Greensburg, PA | Fabricated Metal Product Manufacturing332721 | 20–99 | ◐ LIKELY ACTIVE |
| PFPanhandle Food Sales Inc. | Slovan, PA | Food Manufacturing311412 | — | ◐ LIKELY ACTIVE |
| PCPannier Corp/gibsonia | Gibsonia, PA | Plastics and Rubber Products Manufacturing326112 | — | ◐ LIKELY ACTIVE |
| PPParker Plastics CORP | Pittsburgh, PA | Plastics and Rubber Products Manufacturing326199 | — | ◐ LIKELY ACTIVE |
| PSParma Sausage Products, INC. | Pittsburgh, PA | Food Manufacturing311612 | — | ◐ LIKELY ACTIVE |
| PTPennsylvania Transformer Technologies, LLC - Canonsburg, PA | Canonsburg, PA | Fabricated Metal Product Manufacturing332420 | 100–499 | ◐ LIKELY ACTIVE |
Penn United Technologies, Inc (Building 10 Location) | Sarver, PA | Fabricated Metal Product Manufacturing332813 | 20–99 | ◐ LIKELY ACTIVE |
| PPPiad Precision Casting Corporation | Greensburg, PA | Primary Metal Manufacturing331423 | 100–499 | ◐ LIKELY ACTIVE |
| PPPittsburgh Plug & Products CORP | Evans City, PA | Fabricated Metal Product Manufacturing332510 | 20–99 | ◐ LIKELY ACTIVE |
| PCPlum CORP | Greensburg, PA | Primary Metal Manufacturing331221 | — | ◐ LIKELY ACTIVE |
| PPPrecision Plating Co/new Castle | New Castle, PA | Fabricated Metal Product Manufacturing332813 | — | ◐ LIKELY ACTIVE |
| PBPrimo Brands Carnegie | Carnegie, PA | Beverage and Tobacco Product Manufacturing312112 | — | ◐ LIKELY ACTIVE |
| QUQEMETICA US Silica - Monroeville | Monroeville, PA | Chemical Manufacturing325180 | 1–19 | ◐ LIKELY ACTIVE |