| MLMelar Litho INC | Chicago | IL | Printing and Related Support Activities323110 | — | ◇ UNVERIFIED |
| MIMenard INC | Chicago | IL | Chemical Manufacturing325611 | — | ◇ UNVERIFIED |
| MFMetal Finishing Research CORP | Chicago | IL | Chemical Manufacturing325998 | — | ◇ UNVERIFIED |
| MTMetromedia Technologies INC | Chicago | IL | Printing and Related Support Activities323110 | — | ◇ UNVERIFIED |
| MPMetropolitan Pier & Exposition Authority | Chicago | IL | Miscellaneous Manufacturing339999 | — | ◇ UNVERIFIED |
| MBMetz Baking CO | Chicago | IL | Food Manufacturing311812 | — | ◇ UNVERIFIED |
| MIMeyer Industrial Container | Chicago | IL | Paper Manufacturing322221 | — | ◇ UNVERIFIED |
| MMMidland Metals Products | Chicago | IL | Fabricated Metal Product Manufacturing332999 | — | ◇ UNVERIFIED |
| MAMidway Airport Amc Buildings | Chicago | IL | Miscellaneous Manufacturing339999 | — | ◇ UNVERIFIED |
| MFMidwest Folding Products | Chicago | IL | Furniture and Related Product Manufacturing337127 | — | ◇ UNVERIFIED |
| MAMike's Anodizing CO | Chicago | IL | Fabricated Metal Product Manufacturing332813 | — | ◇ UNVERIFIED |
| MIMilton Industires INC | Chicago | IL | Plastics and Rubber Products Manufacturing326299 | — | ◇ UNVERIFIED |
| MLMixonsite LLC | Chicago | IL | Miscellaneous Manufacturing339999 | — | ◇ UNVERIFIED |
| MDModern Die Casting CORP | Chicago | IL | Primary Metal Manufacturing331521 | — | ◇ UNVERIFIED |
| MAMorse Automotive CORP | Chicago | IL | Transportation Equipment Manufacturing336390 | — | ◇ UNVERIFIED |
| MAMorse Automotive CORP | Chicago | IL | Transportation Equipment Manufacturing336390 | — | ◇ UNVERIFIED |
| MPMrc Polymers INC | Chicago | IL | Chemical Manufacturing325211 | — | ◇ UNVERIFIED |
| MPMrc Polymers INC | Chicago | IL | Miscellaneous Manufacturing339999 | — | ◇ UNVERIFIED |
| NCNalco Chemical CO | Chicago | IL | Petroleum and Coal Products Manufacturing324191 | — | ◇ UNVERIFIED |
| NCNarchem CORP | Chicago | IL | Chemical Manufacturing325188 | — | ◇ UNVERIFIED |
| NCNational Casein CO | Chicago | IL | Chemical Manufacturing325520 | — | ◇ UNVERIFIED |
| NINational Interchem CORP | Chicago | IL | Chemical Manufacturing325612 | — | ◇ UNVERIFIED |
| NFNatures Fynd | Chicago | IL | Food Manufacturing311999 | — | ◇ UNVERIFIED |
| NCNazdar Chicago | Chicago | IL | Chemical Manufacturing325910 | — | ◇ UNVERIFIED |
| NLNcm LLC | Chicago | IL | Food Manufacturing311611 | — | ◇ UNVERIFIED |
| NRNehi Royal Crown CORP | Chicago | IL | Beverage and Tobacco Product Manufacturing312111 | — | ◇ UNVERIFIED |
| NHNelson Harkins Industries | Chicago | IL | Printing and Related Support Activities323113 | — | ◇ UNVERIFIED |
| NPNew Packing CO | Chicago | IL | Food Manufacturing311612 | — | ◇ UNVERIFIED |
| NCNewsweb CORP | Chicago | IL | Printing and Related Support Activities323111 | — | ◇ UNVERIFIED |
| NHN Henry & Son INC | Chicago | IL | Apparel Manufacturing315990 | — | ◇ UNVERIFIED |
| NCNichem CORP | Chicago | IL | Miscellaneous Manufacturing339999 | — | ◇ UNVERIFIED |
| NENina Enterprises INC | Chicago | IL | Fabricated Metal Product Manufacturing332116 | — | ◇ UNVERIFIED |
| NANorth American Salt CO | Chicago | IL | Chemical Manufacturing325998 | — | ◇ UNVERIFIED |
| NANorth American Stevedoring CO (formerly Ceres) | Chicago | IL | Miscellaneous Manufacturing339999 | — | ◇ UNVERIFIED |
| NPNorthwestern Plating Works | Chicago | IL | Chemical Manufacturing325199 | — | ◇ UNVERIFIED |
| OAOgden Avenue Materials INC | Chicago | IL | Petroleum and Coal Products Manufacturing324121 | — | ◇ UNVERIFIED |
| OCO'hare Concrete Plant | Chicago | IL | Petroleum and Coal Products Manufacturing324121 | — | ◇ UNVERIFIED |
| OFOn-cor Frozen Foods, LLC | Chicago | IL | Food Manufacturing311411 | — | ◇ UNVERIFIED |
| OMOremus Material LLC | Chicago | IL | Nonmetallic Mineral Product Manufacturing327320 | — | ◇ UNVERIFIED |
| OLOrganics LLC | Chicago | IL | Chemical Manufacturing325412 | — | ◇ UNVERIFIED |
| OFOriginal Ferrara INC | Chicago | IL | Food Manufacturing311812 | — | ◇ UNVERIFIED |
| OIOrion Industries & Related Entities | Chicago | IL | Fabricated Metal Product Manufacturing332812 | — | ◇ UNVERIFIED |
| OLOrion Lubricant | Chicago | IL | Textile Mills313310 | — | ◇ UNVERIFIED |
| OOsi | Chicago | IL | Furniture and Related Product Manufacturing337211 | — | ◇ UNVERIFIED |
| OBOzinga Bros INC | Chicago | IL | Miscellaneous Manufacturing339999 | — | ◇ UNVERIFIED |
| OROzinga Ready Mix - 103rd St Plant | Chicago | IL | Nonmetallic Mineral Product Manufacturing327320 | — | ◇ UNVERIFIED |
| PCPackaging CORP of America | Chicago | IL | Paper Manufacturing322211 | — | ◇ UNVERIFIED |
| PCPallet City INC | Chicago | IL | Wood Product Manufacturing321920 | — | ◇ UNVERIFIED |
| PPPalmer Printing INC | Chicago | IL | Printing and Related Support Activities323111 | — | ◇ UNVERIFIED |
| PSParagon Spring and Stamping CO | Chicago | IL | Fabricated Metal Product Manufacturing332612 | — | ◇ UNVERIFIED |
