| MIMatthews Intl Marking Products Division | Blawnox | PA | Chemical Manufacturing325910 | — | ◇ UNVERIFIED |
| MSMcclain Stone CO. INC. Brooklyn Saw Shop | Kingsley | PA | Nonmetallic Mineral Product Manufacturing327991 | — | ◇ UNVERIFIED |
| MGMcdermitt Gettysburg Concrete & Blacktop Plts | Gettysburg | PA | Petroleum and Coal Products Manufacturing324121 | — | ◇ UNVERIFIED |
| MRMckees Rocks Transfer Station | Mckees Rocks | PA | Chemical Manufacturing325998 | — | ◇ UNVERIFIED |
| MPMckinney Products | Scranton | PA | Fabricated Metal Product Manufacturing332439 | — | ◇ UNVERIFIED |
| MBMclanahan Beaver Street Facility | Hollidaysburg | PA | Machinery Manufacturing333131 | — | ◇ UNVERIFIED |
| MAMcminns Asphalt CO INC Mason Dixon Plt | Peach Bottom | PA | Petroleum and Coal Products Manufacturing324121 | — | ◇ UNVERIFIED |
| MPMd Pharmaceutical Supply | Hanover | PA | Chemical Manufacturing325320 | — | ◇ UNVERIFIED |
| MLMeckleys Limestone Prod/beavertown Asphalt Plt | Middleburg | PA | Petroleum and Coal Products Manufacturing324121 | — | ◇ UNVERIFIED |
| MIMedrad INC | Indianola | PA | Miscellaneous Manufacturing339112 | — | ◇ UNVERIFIED |
| MIMedrad INC Heilman Center | Pittsburgh | PA | Computer and Electronic Product Manufacturing334513 | — | ◇ UNVERIFIED |
| MAMelick Aquafeeds Inc/catawissa Fish Food Plt | Catawissa | PA | Food Manufacturing311119 | — | ◇ UNVERIFIED |
| MCMellott Co/cedar Hill Quarry | Peach Bottom | PA | Nonmetallic Mineral Product Manufacturing327992 | — | ◇ UNVERIFIED |
| MCMellott Co/warfordsburg Mfg Fac | Warfordsburg | PA | Machinery Manufacturing333120 | — | ◇ UNVERIFIED |
 Mercer Spring & Wire/townville | Townville | PA | Fabricated Metal Product Manufacturing332611 | — | ◇ UNVERIFIED |
| MPMercury Printing | Wilkinsburg | PA | Printing and Related Support Activities323111 | — | ◇ UNVERIFIED |
| MLMesser LLC | Tobyhanna | PA | Chemical Manufacturing325120 | — | ◇ UNVERIFIED |
| MFMessick Farm Equipment | Elizabethtown | PA | Fabricated Metal Product Manufacturing332216 | — | ◇ UNVERIFIED |
| MBMetal Bank of America | Philadelphia | PA | Primary Metal Manufacturing331420 | — | ◇ UNVERIFIED |
| MSMetaldyne Sintered Ridgway LLC | Emporium | PA | Primary Metal Manufacturing331110 | — | ◇ UNVERIFIED |
| MEMetalor Electrotechnics USA Corp/plt 5 | Delmont | PA | Primary Metal Manufacturing331491 | — | ◇ UNVERIFIED |
| MSMetropolitan Steel I/steelco | Sinking Spring | PA | Fabricated Metal Product Manufacturing332312 | — | ◇ UNVERIFIED |
| MMMetso Minerals Ind INC | York | PA | Machinery Manufacturing333131 | — | ◇ UNVERIFIED |
| MPMetso Paper USA Inc/clarks Summit Svc Ctr | Clarks Summit | PA | Plastics and Rubber Products Manufacturing326299 | — | ◇ UNVERIFIED |
| MFMeyer Frank C Pkg | Jeannette | PA | Paper Manufacturing322212 | — | ◇ UNVERIFIED |
| MLMicrobac Laboratories | Harrisburg | PA | Electrical Equipment, Appliance & Component Manufacturing335313 | — | ◇ UNVERIFIED |
 Micross Components/hatfield | Hatfield | PA | Computer and Electronic Product Manufacturing334419 | — | ◇ UNVERIFIED |
| MCMid-atlantic Circuits, INC. | Ivyland | PA | Computer and Electronic Product Manufacturing334412 | — | ◇ UNVERIFIED |
| MBMiddletown Biofuels LLC | Middletown | PA | Food Manufacturing311225 | — | ◇ UNVERIFIED |
| MMMi-kee-tro Metal Mfg | York | PA | Fabricated Metal Product Manufacturing332322 | — | ◇ UNVERIFIED |
| MAMikes Auto Refinishing/prospect Park | Prospect Park | PA | Electrical Equipment, Appliance & Component Manufacturing335220 | — | ◇ UNVERIFIED |
 Milford Enterprises Mfg | Quakertown | PA | Furniture and Related Product Manufacturing337110 | — | ◇ UNVERIFIED |
| MTMillcreek Twp/erie | Erie | PA | Petroleum and Coal Products Manufacturing324121 | — | ◇ UNVERIFIED |
| MCMiller Casket Co/jermyn | Jermyn | PA | Miscellaneous Manufacturing339995 | — | ◇ UNVERIFIED |
| MAMillers Auto Sales & Service INC | Dillsburg | PA | Petroleum and Coal Products Manufacturing324191 | — | ◇ UNVERIFIED |
 Miller Welding & Machine CO | Brookville | PA | Fabricated Metal Product Manufacturing332710 | — | ◇ UNVERIFIED |
| MRMiltec Resources Uss Edgar Thomson Works | Braddock | PA | Primary Metal Manufacturing331110 | — | ◇ UNVERIFIED |
| MPMi Profiles LLC - Millersburg | Millersburg | PA | Plastics and Rubber Products Manufacturing326121 | — | ◇ UNVERIFIED |
| MPMi Profiles Llc/millersburg Plt | Millersburg | PA | Plastics and Rubber Products Manufacturing326121 | — | ◇ UNVERIFIED |
| MCMitsubishi Chem Advanced Material Laurel Line Mfg/scranton | Scranton | PA | Plastics and Rubber Products Manufacturing326113 | — | ◇ UNVERIFIED |
| MCMitsubishi Chem Advanced Materials Inc/delmont 4 | Delmont | PA | Plastics and Rubber Products Manufacturing326113 | — | ◇ UNVERIFIED |
| MZMitsui Zinc Powder | Monaca | PA | Primary Metal Manufacturing331410 | — | ◇ UNVERIFIED |
| MWMi Windows & Doors LLC -gratz Facility | Gratz | PA | Plastics and Rubber Products Manufacturing326199 | — | ◇ UNVERIFIED |
| MLMobile Lifts INC | Collegeville | PA | Machinery Manufacturing333922 | — | ◇ UNVERIFIED |
| MOMobile Outfitters, LLC | Philadelphia | PA | Computer and Electronic Product Manufacturing334210 | — | ◇ UNVERIFIED |
| MCModel City Clnr/pennbrook | Harrisburg | PA | Printing and Related Support Activities323117 | — | ◇ UNVERIFIED |
| MCModern Clnr/ephrata | Ephrata | PA | Fabricated Metal Product Manufacturing332998 | — | ◇ UNVERIFIED |
| MIModlogiq INC Modular Building Specialists | New Holland | PA | Fabricated Metal Product Manufacturing332311 | — | ◇ UNVERIFIED |
| MAMolded Acoustical Prod of Easton Inc/easton | Easton | PA | Plastics and Rubber Products Manufacturing326121 | — | ◇ UNVERIFIED |
| MAMolded Acoustical Products of Easton, INC. | Easton | PA | Nonmetallic Mineral Product Manufacturing327993 | 500+ | ◇ UNVERIFIED |
