Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Security and Safety Training Institute | School | 181 | Cook | 41 53 03 N | 087 37 44 W |
| Security Club Lake | Reservoir | 125 | Perry | 37 57 55 N | 089 14 49 W |
| Security Schools | School | 181 | Cook | 41 52 38 N | 087 37 45 W |
| Sedan Prairie School | School | 215 | Cook | 41 31 43 N | 087 46 00 W |
| Sedan Station (historical) | Locale | 148 | Mason | 40 13 56 N | 090 02 25 W |
| Sedgwick Park | Park | 195 | Cook | 41 48 11 N | 087 51 40 W |
| Sediment Control Structure Pond Number 22 | Reservoir | 211 | Henderson | 40 51 30 N | 090 47 18 W |
| Sediment Control Structure Pond Number 22 Dam | Dam | 211 | Henderson | 40 51 30 N | 090 47 18 W |
| Sedwick School (historical) | School | 222 | Mercer | 41 07 28 N | 090 35 21 W |
| Seed Chapel | Church | 145 | Crawford | 38 56 46 N | 087 55 00 W |
| Seed Creek | Stream | | Lawrence | 38 39 02 N | 087 47 46 W |
| Seed Elementary School | School | 144 | Lawrence | 38 42 38 N | 087 45 24 W |
| Seedorf School (historical) | School | 189 | Kankakee | 41 05 04 N | 087 52 06 W |
| Seehorn | Populated Place | 145 | Pike | 39 45 19 N | 091 15 41 W |
| Seeley G. Mudd Science and Engineering Library | Building | 179 | Cook | 42 03 30 N | 087 40 28 W |
| Seeman Airport | Airport | 208 | Livingston | 40 46 43 N | 088 39 58 W |
| Seepage Ditch | Canal | 143 | Adams | 40 08 39 N | 091 27 56 W |
| Sefton | Populated Place | 172 | Fayette | 39 04 15 N | 088 57 20 W |
| Sefton Townhall | Building | 168 | Fayette | 39 02 30 N | 088 59 00 W |
| Seguin School | School | 187 | Cook | 41 49 56 N | 087 46 46 W |
| Seguin Training School | School | 184 | Cook | 41 50 07 N | 087 45 38 W |
| Seibert School (historical) | School | 158 | Madison | 38 50 29 N | 089 47 48 W |
| Seigel School (historical) | School | 226 | Adams | 39 52 53 N | 091 08 45 W |
| Seigert Station (historical) | Locale | 132 | Edwards | 38 18 48 N | 087 58 48 W |
| Seigfried Halfpap Airport | Airport | 162 | Adams | 39 53 10 N | 091 19 15 W |
| Seipp School (historical) | School | 207 | La Salle | 41 07 14 N | 088 59 22 W |
| Seiter Park | Park | 202 | Cook | 41 30 06 N | 087 37 07 W |
| Seitz Landing Strip | Airport | 194 | Christian | 39 24 45 N | 089 30 51 W |
| Seitz Quarry | Mine | 255 | Ogle | 42 01 00 N | 089 18 33 W |
| Selans Beauty School | School | 181 | Cook | 41 52 59 N | 087 37 41 W |
| Selans Beauty School | School | 185 | Cook | 41 41 08 N | 087 37 14 W |
| Selans Beauty School | School | 189 | Cook | 41 56 17 N | 087 46 09 W |
| Selans Beauty School | School | 194 | Cook | 41 53 17 N | 087 48 23 W |
| Selans Schools of Modern Electrolysis Sales | School | 189 | Cook | 41 56 17 N | 087 46 09 W |
| Selans Schools of Modern Electrolysis Sales | School | 194 | Cook | 41 53 17 N | 087 48 23 W |
| Selby School (historical) | School | 135 | Wayne | 38 35 19 N | 088 27 28 W |
| Selbytown | Locale | 180 | Sangamon | 39 55 36 N | 089 34 21 W |
| Selenas House of Beauty and School of Hair Weev Technology | School | 181 | Cook | 41 52 56 N | 087 37 39 W |
| Selenas House of Beauty and School of Hair Weev Technology | School | 180 | Cook | 41 44 38 N | 087 36 46 W |
| Sell Cemetery | Cemetery | 191 | Macoupin | 39 16 41 N | 089 59 56 W |
| Seller Mine | Mine | 205 | Fulton | 40 33 30 N | 090 10 43 W |
| Sellers | Populated Place | 212 | Champaign | 40 11 11 N | 088 06 17 W |
| Sellers Airport | Airport | 204 | La Salle | 41 30 50 N | 088 56 15 W |
| Sellers Landing | Locale | 102 | Hardin | 37 32 56 N | 088 06 00 W |
| Selma (historical) | Populated Place | 119 | Wabash | 38 25 33 N | 087 44 53 W |
| Selma Ditch | Canal | 118 | Monroe | 38 12 27 N | 090 17 25 W |
| Selmaville | Populated Place | 163 | Marion | 38 36 25 N | 088 59 43 W |
| Selmaville South School | School | 162 | Marion | 38 35 24 N | 089 00 01 W |
| Selock School (historical) | School | 229 | Ford | 40 31 52 N | 088 15 09 W |
| Selsor Ford | Crossing | 192 | Vermilion | 40 15 32 N | 087 47 43 W |
| Selsor Ford | Crossing | 190 | Vermilion | 40 15 32 N | 087 47 42 W |
| Selwyn Theater | Building | 182 | Cook | 41 53 08 N | 087 37 47 W |
| Semet Solvay Slip | Locale | 178 | Cook | 41 41 39 N | 087 33 16 W |
| Seminary | Populated Place | 133 | Richland | 38 35 01 N | 088 07 35 W |
| Seminary Avenue Community Church | Church | 182 | Cook | 41 55 42 N | 087 39 23 W |
| Seminary Cemetery | Cemetery | 152 | Fayette | 38 52 27 N | 089 10 31 W |
| Seminary Consortium for Urban Pastoral Education | School | 180 | Cook | 41 53 48 N | 087 37 45 W |
| Seminary Creek | Stream | | Clay | 38 36 51 N | 088 25 11 W |
| Seminary Creek | Stream | | Greene | 39 23 05 N | 090 23 15 W |
| Seminary Fork | Stream | | Union | 37 32 16 N | 089 19 55 W |
| Seminary Park | Park | 274 | McHenry | 42 13 37 N | 088 20 43 W |
| Seminary School | School | 149 | Clay | 38 40 13 N | 088 29 37 W |
| Seminary School (historical) | School | 153 | Fayette | 38 52 44 N | 089 10 31 W |
| Seminary School (historical) | School | 157 | Hamilton | 38 04 52 N | 088 38 56 W |
| Seminary School (historical) | School | 132 | Richland | 38 35 02 N | 088 07 53 W |
| Seminary School (historical) | School | 177 | Scott | 39 41 43 N | 090 26 16 W |
| Seminary Square | Park | 165 | Madison | 38 53 33 N | 090 10 44 W |
| Seminary Street Public School (historical) | School | 204 | Vermilion | 39 58 31 N | 087 37 48 W |
| Seminary Tabernacle (historical) | Church | 133 | Richland | 38 34 10 N | 088 07 36 W |
| Seminole Park | Park | 259 | Cook | 42 05 44 N | 088 07 40 W |
| Sen Beck Ditch | Canal | 104 | Massac | 37 15 31 N | 088 46 54 W |
| Senachwine Creek | Stream | | Peoria | 40 55 46 N | 089 27 48 W |
| Senachwine Creek | Stream | | Putnam | 41 11 52 N | 089 22 25 W |
| Senachwine Lake | Lake | 134 | Putnam | 41 10 07 N | 089 20 19 W |
| Senachwine School (historical) | School | 194 | Marshall | 41 01 00 N | 089 30 21 W |
| Senachwine School (historical) | School | 159 | Peoria | 40 56 40 N | 089 30 04 W |
| Senate Island | Island | 133 | Fulton | 40 27 02 N | 089 54 34 W |
| Seneca | Populated Place | 155 | La Salle | 41 18 40 N | 088 36 35 W |
| Seneca Elementary School | School | 153 | La Salle | 41 18 49 N | 088 36 22 W |
| Seneca High School | School | 154 | La Salle | 41 18 31 N | 088 36 27 W |
| Seneca Park | Park | 180 | Cook | 41 53 49 N | 087 37 22 W |
| Seneca Park | Park | 184 | Cook | 42 02 24 N | 087 43 45 W |
| Senesac School (historical) | School | 199 | Kankakee | 41 10 39 N | 087 48 46 W |
| Senior Citizen Memorial Park | Park | 181 | Cook | 41 55 23 N | 087 41 08 W |
| Senka Park | Park | 186 | Cook | 41 47 26 N | 087 42 42 W |
| Senn Metro Academy | School | 180 | Cook | 41 59 21 N | 087 40 00 W |
| Senn Park | Park | 181 | Cook | 41 59 20 N | 087 40 05 W |
| Sentel School (historical) | School | 132 | Clinton | 38 33 10 N | 089 34 20 W |
| Senteney School (historical) | School | 203 | Coles | 39 37 19 N | 088 24 03 W |
| Sentinel Nature Preserve | Park | 241 | Carroll | 42 07 33 N | 090 09 12 W |
| Sentinel Park | Park | 225 | DuPage | 41 48 27 N | 087 59 05 W |
| Sepo | Populated Place | 138 | Fulton | 40 20 37 N | 090 07 09 W |
| Sepo Creek | Stream | | Fulton | 40 20 48 N | 090 07 17 W |
| Sequoia Park | Park | 191 | Cook | 42 02 58 N | 087 45 33 W |
| Sequoit Creek | Stream | | Lake | 42 28 42 N | 088 06 46 W |
| Serbian Eastern Orthodox Church of Saint Archangel Michael | Church | 180 | Cook | 41 43 01 N | 087 33 03 W |
| Serbian Monastery Cemetery | Cemetery | 209 | Lake | 42 19 56 N | 087 57 05 W |
| Serbian Saint Simeon Mirotociv Orthodox Church | Church | 178 | Cook | 41 41 16 N | 087 31 56 W |
| Serena | Populated Place | 193 | La Salle | 41 29 10 N | 088 43 53 W |
| Serena Elementary School | School | 193 | La Salle | 41 29 16 N | 088 43 48 W |
| Serena High School | School | 193 | La Salle | 41 29 16 N | 088 43 52 W |
| Serena Hills Elementary School | School | 203 | Cook | 41 31 59 N | 087 39 11 W |
| Serena Post Office | Post Office | 193 | La Salle | 41 29 10 N | 088 43 59 W |
| Serena United Methodist Church | Church | 192 | La Salle | 41 29 07 N | 088 44 09 W |
| Serene Lake | Lake | 128 | Perry | 38 00 35 N | 089 24 53 W |
| Sergeant Means Park | Park | 211 | Cook | 41 30 44 N | 087 40 41 W |
| Serrot Cemetery | Cemetery | 171 | Schuyler | 40 02 38 N | 090 34 17 W |
| Sertoma Job Training Center | School | 181 | Cook | 41 40 07 N | 087 43 40 W |
| Servant of God Episcopal Church | Church | 182 | Cook | 41 50 13 N | 087 37 20 W |
| Servant of Mary Convent | Church | 187 | Will | 41 34 28 N | 088 13 26 W |