| MMMartin Marietta - Pueblo Asphalt Plant | Pueblo | CO | Petroleum and Coal Products Manufacturing324121 | — | ◇ UNVERIFIED |
| MMMartin Marietta Rigden Ready Mix | Fort Collins | CO | Nonmetallic Mineral Product Manufacturing327320 | — | ◇ UNVERIFIED |
| MPMartin Plastic Converters INC | Englewood | CO | Plastics and Rubber Products Manufacturing326130 | — | ◇ UNVERIFIED |
| MWMaster Wash | Commerce City | CO | Chemical Manufacturing325998 | — | ◇ UNVERIFIED |
| MCMathias Concrete - Alamosa Plant | Alamosa | CO | Nonmetallic Mineral Product Manufacturing327331 | — | ◇ UNVERIFIED |
| MCMathias Concrete - South Fork | South Fork | CO | Nonmetallic Mineral Product Manufacturing327320 | — | ◇ UNVERIFIED |
| MBMaverick Biofuels, INC. - M2 Facility | Denver | CO | Chemical Manufacturing325193 | — | ◇ UNVERIFIED |
| MCMcatee Construction Co- Riverside | Sterling | CO | Nonmetallic Mineral Product Manufacturing327310 | — | ◇ UNVERIFIED |
| MCMcatee Const - Sterling Asphalt Plant | Sterling | CO | Petroleum and Coal Products Manufacturing324121 | — | ◇ UNVERIFIED |
| MAMccormick Armstrong | Colorado Springs | CO | Printing and Related Support Activities323111 | — | ◇ UNVERIFIED |
| MEMccormick Excav & Paving - Colorado Ave | Burlington | CO | Petroleum and Coal Products Manufacturing324121 | — | ◇ UNVERIFIED |
| MEMccormick Exc & Paving - Port Hm Asphalt | Stratton | CO | Petroleum and Coal Products Manufacturing324121 | — | ◇ UNVERIFIED |
| MFMcdonald Farms Enterprizes INC | Denver | CO | Food Manufacturing311000 | — | ◇ UNVERIFIED |
| MDMcdonnell Douglas Astronautics CO | Pueblo | CO | Transportation Equipment Manufacturing336413 | — | ◇ UNVERIFIED |
| MFMears Fertilizer, INC. - Unit 1 | Monte Vista | CO | Chemical Manufacturing325314 | — | ◇ UNVERIFIED |
 Medegen Medical Products, LLC | Northglenn | CO | Plastics and Rubber Products Manufacturing326199 | — | ◇ UNVERIFIED |
| MCMerck & Co, LLC | Boulder | CO | Plastics and Rubber Products Manufacturing326199 | — | ◇ UNVERIFIED |
| MTMercury Tube - 3211 W Bear Creek Dr | Englewood | CO | Primary Metal Manufacturing331210 | — | ◇ UNVERIFIED |
| MOMesa Oil INC | Arvada W of | CO | Petroleum and Coal Products Manufacturing324110 | — | ◇ UNVERIFIED |
| MOMesa Oil INC | Arvada | CO | Miscellaneous Manufacturing339999 | — | ◇ UNVERIFIED |
| MLMesser LLC | Cortez | CO | Chemical Manufacturing325120 | — | ◇ UNVERIFIED |
| MPMetal Packaging International | Northglenn | CO | Fabricated Metal Product Manufacturing332431 | — | ◇ UNVERIFIED |
| MIMetaltech Industries INC | Longmont | CO | Fabricated Metal Product Manufacturing332322 | — | ◇ UNVERIFIED |
| MGMetre - General INC | Frederick | CO | Machinery Manufacturing333319 | — | ◇ UNVERIFIED |
| MMMetso Minerals Pumps & Process | Colorado Springs | CO | Machinery Manufacturing333131 | — | ◇ UNVERIFIED |
| MMMicro Metals | Colorado Springs | CO | Fabricated Metal Product Manufacturing332322 | — | ◇ UNVERIFIED |
| MAMid America Agriproducts-haxtun | Haxtun Area | CO | Petroleum and Coal Products Manufacturing324110 | — | ◇ UNVERIFIED |
| MAMid America Plating | Denver | CO | Fabricated Metal Product Manufacturing332813 | — | ◇ UNVERIFIED |
| MPMido Printing | Denver | CO | Printing and Related Support Activities323110 | — | ◇ UNVERIFIED |
| MFMidwest Farms, LLC | Burlington | CO | Food Manufacturing311119 | — | ◇ UNVERIFIED |
 Midwest Rubber & Supply CO | Denver | CO | Plastics and Rubber Products Manufacturing326220 | — | ◇ UNVERIFIED |
| MAMikron Assembly Technology | Aurora | CO | Machinery Manufacturing333248 | — | ◇ UNVERIFIED |
| MHMile High Labs, INC | Broomfield | CO | Chemical Manufacturing325412 | — | ◇ UNVERIFIED |
| MMMile-hi Machine, INC. | Arvada | CO | Fabricated Metal Product Manufacturing332710 | — | ◇ UNVERIFIED |
| MLMillercoors - Longmont | Longmont | CO | Beverage and Tobacco Product Manufacturing312120 | — | ◇ UNVERIFIED |
| MPMiller Press INC | Denver | CO | Printing and Related Support Activities323110 | — | ◇ UNVERIFIED |
| MWMillstone Weber - Concrete Plant #7001 | Denver | CO | Nonmetallic Mineral Product Manufacturing327320 | — | ◇ UNVERIFIED |
| MSMillwright Services | Fort Morgan | CO | Machinery Manufacturing333992 | — | ◇ UNVERIFIED |
| MIMinco Incorporated | Colorado Springs | CO | Fabricated Metal Product Manufacturing332812 | — | ◇ UNVERIFIED |
| MLMisb, LLC | Colorado Springs | CO | Nonmetallic Mineral Product Manufacturing327991 | — | ◇ UNVERIFIED |
| MFMission Foods CORP - 2110 Santa Fe Drive | Pueblo Area | CO | Food Manufacturing311830 | — | ◇ UNVERIFIED |
| MAMizkan Americas-pickel Mfg | La Junta | CO | Food Manufacturing311421 | — | ◇ UNVERIFIED |
| MCM.K. Custom Fabrication LLC | Parker | CO | Fabricated Metal Product Manufacturing332710 | — | ◇ UNVERIFIED |
| MEMmi Etoh INC | Golden | CO | Chemical Manufacturing325193 | — | ◇ UNVERIFIED |
| MMM & M Tank & Tower | Greeley | CO | Fabricated Metal Product Manufacturing332420 | — | ◇ UNVERIFIED |
| MMMoffat Mine Service INC. | Craig | CO | Fabricated Metal Product Manufacturing332999 | — | ◇ UNVERIFIED |
| MCMolson Coors - Monte Vista | Monte Vista | CO | Beverage and Tobacco Product Manufacturing312120 | — | ◇ UNVERIFIED |
| MVMonte Vista, CO | Monte Vista | CO | Chemical Manufacturing325311 | — | ◇ UNVERIFIED |
| MCMonticello Cabinetry & Millwork, LTD | Firestone | CO | Furniture and Related Product Manufacturing337127 | — | ◇ UNVERIFIED |
| MCMontrose City | Montrose | CO | Petroleum and Coal Products Manufacturing324121 | — | ◇ UNVERIFIED |
