Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Continental Center | Building | 182 | Cook | 41 52 40 N | 087 37 33 W |
| Continental Heliport | Airport | 180 | Cook | 41 52 18 N | 087 38 25 W |
| Continentale Beauty School | School | 195 | Cook | 41 56 15 N | 087 49 06 W |
| Continential Executive Business Park | Locale | 207 | Lake | 42 12 59 N | 087 56 38 W |
| Contrary Creek | Stream | | Hamilton | 37 56 53 N | 088 25 28 W |
| Contrary School (historical) | School | 198 | Coles | 39 37 22 N | 088 07 35 W |
| Control Data Institute | School | 182 | Cook | 41 53 09 N | 087 37 29 W |
| Control Data Learning Center | School | 181 | Cook | 41 53 10 N | 087 37 29 W |
| Convent Church | Church | 210 | Lake | 42 16 46 N | 087 55 27 W |
| Convent of the Holy Spirit | Church | 201 | Cook | 42 06 16 N | 087 48 00 W |
| Convent Park | Park | 205 | Cook | 41 37 15 N | 087 45 44 W |
| Conway Building | Building | 181 | Cook | 41 52 59 N | 087 37 53 W |
| Conway Church | Church | 124 | Wayne | 38 24 04 N | 088 09 29 W |
| Conway Farms Golf Course | Locale | 211 | Lake | 42 13 58 N | 087 53 23 W |
| Conway School (historical) | School | 120 | Wayne | 38 24 02 N | 088 10 15 W |
| Conwayville (historical) | Populated Place | 138 | Greene | 39 14 10 N | 090 23 57 W |
| Cooch Landing Area | Airport | 208 | Douglas | 39 50 30 N | 088 27 30 W |
| Cook Avenue School | School | 187 | Cook | 41 43 08 N | 087 45 08 W |
| Cook Bridge (historical) | Bridge | 183 | Moultrie | 39 35 39 N | 088 43 36 W |
| Cook Cemetery | Cemetery | 169 | Edgar | 39 41 58 N | 087 32 02 W |
| Cook Cemetery | Cemetery | 180 | Fayette | 39 03 40 N | 089 12 52 W |
| Cook Cemetery | Cemetery | 133 | Franklin | 37 57 58 N | 089 06 24 W |
| Cook Cemetery | Cemetery | 137 | Franklin | 38 00 46 N | 088 42 53 W |
| Cook Cemetery | Cemetery | 128 | Hamilton | 37 56 44 N | 088 23 06 W |
| Cook Cemetery | Cemetery | 183 | Hancock | 40 16 50 N | 091 14 56 W |
| Cook Cemetery | Cemetery | 195 | Knox | 40 48 38 N | 090 13 26 W |
| Cook Cemetery | Cemetery | 101 | Pulaski | 37 07 27 N | 089 06 54 W |
| Cook County | Civil | 189 | Cook | 41 50 00 N | 087 51 00 W |
| Cook County Building | Building | 182 | Cook | 41 53 02 N | 087 37 53 W |
| Cook County Circuit Courthouse | Building | 190 | Cook | 42 03 48 N | 087 46 07 W |
| Cook County Courthouse | Building | 182 | Cook | 41 52 43 N | 087 37 44 W |
| Cook County Courthouse | Building | 190 | Cook | 41 35 24 N | 087 41 34 W |
| Cook County Criminal Courthouse | Building | 182 | Cook | 41 50 36 N | 087 41 45 W |
| Cook County Forest Preserve | Park | 189 | Cook | 41 33 43 N | 087 35 18 W |
| Cook County Graduate School of Medicine | School | 181 | Cook | 41 52 20 N | 087 40 16 W |
| Cook County Hospital | Hospital | 181 | Cook | 41 52 25 N | 087 40 22 W |
| Cook Elementary School | School | 184 | Cook | 41 44 43 N | 087 39 35 W |
| Cook Family Cemetery | Cemetery | 177 | Madison | 38 44 18 N | 089 56 15 W |
| Cook Hall | Building | 242 | McLean | 40 30 33 N | 088 59 32 W |
| Cook Harbor | Bay | 128 | Mason | 40 18 26 N | 090 03 55 W |
| Cook Memorial Park | Park | 241 | Lake | 42 16 13 N | 088 08 32 W |
| Cook School (historical) | School | 206 | Bureau | 41 24 03 N | 089 41 03 W |
| Cook School (historical) | School | 217 | Champaign | 40 16 10 N | 088 01 17 W |
| Cook School (historical) | School | 185 | Knox | 40 48 47 N | 090 13 44 W |
| Cook School (historical) | School | 209 | Lee | 41 48 25 N | 089 33 11 W |
| Cook School (historical) | School | 201 | Moultrie | 39 35 41 N | 088 44 28 W |
| Cook School (historical) | School | 242 | Ogle | 42 03 19 N | 088 59 59 W |
| Cook School (historical) | School | 177 | Rock Island | 41 32 10 N | 090 22 35 W |
| Cook School (historical) | School | 146 | Wayne | 38 31 01 N | 088 30 29 W |
| Cook School (historical) | School | 118 | White | 38 05 51 N | 088 08 20 W |
| Cooke Ranch | Flat | 128 | Greene | 39 16 13 N | 090 35 40 W |
| Cooke School | School | 234 | Knox | 40 56 12 N | 090 22 57 W |
| Cooke School (historical) | School | 231 | Adams | 39 48 54 N | 091 10 20 W |
| Cookes Subdivision | Populated Place | 184 | Cook | 41 40 03 N | 087 37 31 W |
| Cooks Mills | Populated Place | 201 | Coles | 39 34 57 N | 088 24 22 W |
| Cooks Mills Consolidated Oil Field | Oilfield | 201 | Coles | 39 38 10 N | 088 23 06 W |
| Cooksville | Populated Place | 234 | McLean | 40 32 35 N | 088 42 59 W |
| Cooksy School (historical) | School | 149 | Williamson | 37 40 09 N | 088 59 04 W |
| Cooley Cemetery | Cemetery | 252 | Ogle | 41 58 09 N | 089 10 29 W |
| Cooley Vocational High School | School | 180 | Cook | 41 54 15 N | 087 38 15 W |
| Coolidge Creek | Stream | | Winnebago | 42 21 39 N | 089 17 32 W |
| Coolidge Elementary School | School | 183 | Cook | 41 34 16 N | 087 32 02 W |
| Coolidge Junior High School | School | 214 | Rock Island | 41 29 28 N | 090 29 16 W |
| Coolidge Middle School | School | 128 | Madison | 38 43 33 N | 090 07 31 W |
| Coolidge School | School | 183 | Cook | 41 36 27 N | 087 37 38 W |
| Cooling Quarry | Mine | 240 | Winnebago | 42 19 24 N | 089 08 56 W |
| Coon Cove | Bay | 183 | Shelby | 39 27 30 N | 088 46 11 W |
| Coon Creek | Stream | | Boone | 42 15 16 N | 088 47 39 W |
| Coon Creek | Stream | | De Witt | 40 06 27 N | 089 00 47 W |
| Coon Creek | Stream | | Effingham | 38 56 15 N | 088 33 18 W |
| Coon Creek | Stream | | Effingham | 39 01 47 N | 088 41 21 W |
| Coon Creek | Stream | | Iroquois | 40 43 40 N | 087 43 03 W |
| Coon Creek | Stream | | Jersey | 39 02 16 N | 090 33 57 W |
| Coon Creek | Stream | | Jo Daviess | 42 24 13 N | 090 07 38 W |
| Coon Creek | Stream | | Marshall | 40 56 58 N | 089 27 47 W |
| Coon Creek | Stream | | Moultrie | 39 34 03 N | 088 32 29 W |
| Coon Creek | Stream | | Ogle | 42 03 55 N | 089 20 26 W |
| Coon Creek | Stream | | Richland | 38 49 03 N | 088 06 43 W |
| Coon Creek | Stream | | Shelby | 39 26 30 N | 088 45 44 W |
| Coon Creek | Stream | | Stephenson | 42 23 13 N | 089 36 36 W |
| Coon Creek | Stream | | Washington | 38 28 55 N | 089 22 56 W |
| Coon Creek | Stream | | Whiteside | 41 40 24 N | 089 55 45 W |
| Coon Creek | Stream | | Woodford | 40 52 32 N | 089 25 46 W |
| Coon Creek Access Area | Park | 201 | Shelby | 39 27 05 N | 088 45 45 W |
| Coon Creek Ditch | Canal | 198 | Lee | 41 43 29 N | 089 36 45 W |
| Coon Creek School (historical) | School | 160 | Marion | 38 30 25 N | 089 01 59 W |
| Coon Creek School (historical) | School | 271 | Ogle | 42 04 41 N | 089 28 55 W |
| Coon Grove Cemetery | Cemetery | 159 | Mason | 40 24 17 N | 089 48 40 W |
| Coon Hollow | Valley | | Jersey | 39 02 03 N | 090 32 03 W |
| Coon Hollow Island | Island | 134 | Tazewell | 40 31 17 N | 089 51 14 W |
| Coon Island | Island | 135 | Calhoun | 39 19 15 N | 090 48 20 W |
| Coon Island School (historical) | School | 128 | Scott | 39 37 25 N | 090 34 51 W |
| Coon Islands | Island | 223 | McHenry | 42 22 46 N | 088 12 20 W |
| Coon Lake | Lake | 126 | Calhoun | 38 57 07 N | 090 29 24 W |
| Coon Ridge Picnic Area | Locale | 187 | Fayette | 39 09 47 N | 089 08 04 W |
| Coon Ridge School (historical) | School | 140 | Franklin | 37 58 47 N | 088 54 04 W |
| Coon Run | Stream | | Morgan | 39 46 33 N | 090 36 07 W |
| Coon School (historical) | School | 148 | Mason | 40 20 22 N | 089 57 23 W |
| Coon Slough | Gut | 135 | Pike | 39 30 47 N | 091 02 32 W |
| Coon Slough | Stream | | Cass | 40 06 34 N | 090 20 24 W |
| Cooney Cemetery | Cemetery | 195 | Schuyler | 40 06 51 N | 090 32 01 W |
| Cooney Creek | Stream | | Pope | 37 15 06 N | 088 31 20 W |
| Cooney School (historical) | School | 297 | McHenry | 42 22 53 N | 088 29 03 W |
| Coonley Elementary School | School | 181 | Cook | 41 57 19 N | 087 41 02 W |
| Coons Cemetery | Cemetery | 194 | Shelby | 39 16 39 N | 088 32 23 W |
| Coonville School (historical) | School | 232 | Warren | 40 51 52 N | 090 41 05 W |
| Coop Branch | Stream | | Macoupin | 39 12 14 N | 090 05 52 W |
| Cooper | Populated Place | 247 | Tazewell | 40 39 37 N | 089 24 15 W |
| Cooper Cemetery | Cemetery | 189 | Cass | 39 52 26 N | 090 02 11 W |
| Cooper Cemetery | Cemetery | 219 | Cook | 41 36 44 N | 087 51 49 W |