| SASignode APT Roselle | Roselle | IL | Machinery Manufacturing333993 | 100-499 | ◐ LIKELY ACTIVE |
| SCSilgan Containers Rochelle | Rochelle | IL | Fabricated Metal Product Manufacturing332431 | 100-499 | ◐ LIKELY ACTIVE |
| SSingle | Neponset | IL | Machinery Manufacturing333131 | 100-499 | ◐ LIKELY ACTIVE |
| SPSmithfield Packaged Meats | St Charles | IL | Food Manufacturing311612 | 100-499 | ◐ LIKELY ACTIVE |
| SMSolberg Manufacturing Hilltop | Itasca | IL | Machinery Manufacturing333413 | 100-499 | ◐ LIKELY ACTIVE |
| SLSolo Laboratories Inc | Broadview | IL | Chemical Manufacturing325620 | 100-499 | ◐ LIKELY ACTIVE |
| SASolstice Advanced Materials US, INC. | Metropolis | IL | Chemical Manufacturing325180 | 100-499 | ◐ LIKELY ACTIVE |
| SSpo | Pontiac | IL | Printing and Related Support Activities323111 | 100-499 | ◐ LIKELY ACTIVE |
| SWSPT Waukegan | Waukegan | IL | Miscellaneous Manufacturing339113 | 100-499 | ◐ LIKELY ACTIVE |
| SCSRAM - Chicago HQ | Chicago | IL | Transportation Equipment Manufacturing336991 | 100-499 | ◐ LIKELY ACTIVE |
| SAStabilization and Functional Systems Sycamore | Sycamore | IL | Food Manufacturing311514 | 100-499 | ◐ LIKELY ACTIVE |
| SCSt. Charles - Kirk Road | St Charles | IL | Printing and Related Support Activities323111 | 100-499 | ◐ LIKELY ACTIVE |
| SCSt. Charles - Kirk Road | Saint Charles | IL | Printing and Related Support Activities323111 | 100-499 | ◐ LIKELY ACTIVE |
| SCSt. Charles Labels | Saint Charles | IL | Printing and Related Support Activities323111 | 100-499 | ◐ LIKELY ACTIVE |
| SCSt. Charles Labels | St Charles | IL | Printing and Related Support Activities323111 | 100-499 | ◐ LIKELY ACTIVE |
| SCSt. Charles VPP | St Charles | IL | Printing and Related Support Activities323111 | 100-499 | ◐ LIKELY ACTIVE |
| SCSt. Charles VPP | Saint Charles | IL | Printing and Related Support Activities323111 | 100-499 | ◐ LIKELY ACTIVE |
| SMStepan Millsdale | Elwood | IL | Chemical Manufacturing325613 | 100-499 | ◐ LIKELY ACTIVE |
| SYStock Yards Chicago | Aurora | IL | Food Manufacturing311612 | 100-499 | ◐ LIKELY ACTIVE |
Sun Chemical Northlake | Northlake | IL | Chemical Manufacturing325910 | 100-499 | ◐ LIKELY ACTIVE |
| SESunCoke Energy Granite City Operations | Granite City | IL | Petroleum and Coal Products Manufacturing324199 | 100-499 | ◐ LIKELY ACTIVE |
| SSuperheat | New Lenox | IL | Fabricated Metal Product Manufacturing332811 | 100-499 | ◐ LIKELY ACTIVE |
| SASwitchboard Apparatus Inc. | Franklin Park | IL | Electrical Equipment, Appliance & Component Manufacturing335313 | 100-499 | ◐ LIKELY ACTIVE |
| TBTakeda: Bannockburn | Bannockburn | IL | Chemical Manufacturing325414 | 100-499 | ◐ LIKELY ACTIVE |
| TMTalerico Martin 7224 | Summit | IL | Food Manufacturing311812 | 100-499 | ◐ LIKELY ACTIVE |
| TPTaylor Print and Visual Impressions - Bloomington IL - 1 and 2 Hardman - 0105-ILBL1 | Bloomington | IL | Printing and Related Support Activities323111 | 100-499 | ◐ LIKELY ACTIVE |
| TMTCCI Manufacturing | Decatur | IL | Transportation Equipment Manufacturing336390 | 100-499 | ◐ LIKELY ACTIVE |
| TLTeasdale Latin Foods-Hoopeston | Hoopeston | IL | Food Manufacturing311422 | 100-499 | ◐ LIKELY ACTIVE |
| TGTerraSource Global | Belleville | IL | Machinery Manufacturing333131 | 100-499 | ◐ LIKELY ACTIVE |
| TTeutopolis | Teutopolis | IL | Food Manufacturing311211 | 100-499 | ◐ LIKELY ACTIVE |
| TFThrushwood Farms | Galesburg | IL | Food Manufacturing311612 | 100-499 | ◐ LIKELY ACTIVE |
| TMThunderbird Metals North | Elk Grove Village | IL | Fabricated Metal Product Manufacturing332999 | 100-499 | ◐ LIKELY ACTIVE |
| TDTiger Dylac, St. Charles, IL. | Saint Charles | IL | Chemical Manufacturing325510 | 100-499 | ◐ LIKELY ACTIVE |
| TDTiger Dylac, St. Charles, IL. | St. Charles | IL | Chemical Manufacturing325510 | 100-499 | ◐ LIKELY ACTIVE |
| TToluca | Toluca | IL | Food Manufacturing311412 | 100-499 | ◐ LIKELY ACTIVE |
| TITRUMPF Inc - TUSC | Hoffman Estates | IL | Fabricated Metal Product Manufacturing332322 | 100-499 | ◐ LIKELY ACTIVE |
| TTubeway | Carol Stream | IL | Food Manufacturing311991 | 100-499 | ◐ LIKELY ACTIVE |
| TKTurano Knead Dough | Bolingbrook | IL | Food Manufacturing311812 | 100-499 | ◐ LIKELY ACTIVE |
| TDTURF Design, Inc. | Gilberts | IL | Miscellaneous Manufacturing339999 | 100-499 | ◐ LIKELY ACTIVE |
| UMUMG/Del Medical | Bloomingdale | IL | Fabricated Metal Product Manufacturing332119 | 100-499 | ◐ LIKELY ACTIVE |
| UPUniversity Park IC | University Park | IL | Transportation Equipment Manufacturing336212 | 100-499 | ◐ LIKELY ACTIVE |
| UIUSA IL Chicago Plant | Chicago | IL | Chemical Manufacturing325510 | 100-499 | ◐ LIKELY ACTIVE |
| UIUSA IL Flora Plant | Flora | IL | Chemical Manufacturing325510 | 100-499 | ◐ LIKELY ACTIVE |
| UIUSA IL Kankakee Plant | Kankakee | IL | Chemical Manufacturing325510 | 100-499 | ◐ LIKELY ACTIVE |
| UIUSA IL Matteson Plant | Matteson | IL | Chemical Manufacturing325510 | 100-499 | ◐ LIKELY ACTIVE |
| UIUSA IL Moline Plant | Moline | IL | Chemical Manufacturing325510 | 100-499 | ◐ LIKELY ACTIVE |
| UIUSA IL South Holland Plant | South Holland | IL | Chemical Manufacturing325130 | 100-499 | ◐ LIKELY ACTIVE |
| UIUSA IL Wheeling Plant | Wheeling | IL | Chemical Manufacturing325510 | 100-499 | ◐ LIKELY ACTIVE |
| VIValto, Inc. - Channahon Facility | Channahon | IL | Plastics and Rubber Products Manufacturing326199 | 100-499 | ◐ LIKELY ACTIVE |
| VBVBC Biorational Research Center | Libertyville | IL | Chemical Manufacturing325320 | 100-499 | ◐ LIKELY ACTIVE |