Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Mount Zion School (historical) | School | 204 | McDonough | 40 16 51 N | 090 44 06 W |
| Mount Zion School (historical) | School | 237 | McLean | 40 32 39 N | 088 28 42 W |
| Mount Zion School (historical) | School | 183 | Sangamon | 39 43 36 N | 089 43 43 W |
| Mount Zion School (historical) | School | 188 | Schuyler | 40 10 23 N | 090 25 12 W |
| Mount Zion United Brethren Cemetery | Cemetery | 153 | Clay | 38 40 33 N | 088 23 46 W |
| Mount Zion United Methodist Church | Church | 135 | Edwards | 38 18 49 N | 088 04 33 W |
| Mountain Branch | Stream | | Marion | 38 43 20 N | 088 45 57 W |
| Mountain Glen | Populated Place | 136 | Union | 37 31 39 N | 089 17 23 W |
| Mountjoy | Populated Place | 221 | Logan | 40 17 12 N | 089 16 55 W |
| Mounts School (historical) | School | 219 | Champaign | 40 17 48 N | 088 15 09 W |
| Mourning Cemetery | Cemetery | 211 | McDonough | 40 27 39 N | 090 52 56 W |
| Mouson Park | Park | 213 | Rock Island | 41 33 22 N | 090 24 06 W |
| Moutray Cemetery | Cemetery | 129 | Wayne | 38 33 29 N | 088 13 48 W |
| Moutray Slough | Stream | | Wayne | 38 32 49 N | 088 12 23 W |
| Moving Up Missionary Baptist Church | Church | 182 | Cook | 41 51 59 N | 087 42 53 W |
| Mowbray Hall | Building | 209 | McDonough | 40 27 58 N | 090 41 02 W |
| Moweaqua | Populated Place | 193 | Shelby | 39 37 29 N | 089 01 08 W |
| Moweaqua Elementary School | School | 190 | Shelby | 39 37 53 N | 089 01 05 W |
| Moweaqua High School | School | 189 | Shelby | 39 37 53 N | 089 01 03 W |
| Mowens Lake | Reservoir | 182 | Macoupin | 39 08 59 N | 090 03 21 W |
| Mowery Bend | Bend | 161 | Sangamon | 39 47 21 N | 089 29 38 W |
| Moyer Cemetery | Cemetery | 228 | Adams | 40 01 43 N | 091 15 46 W |
| Moyer Cemetery | Cemetery | 196 | Shelby | 39 27 17 N | 088 46 41 W |
| Moyer Library | Building | 229 | Ford | 40 28 04 N | 088 22 32 W |
| Moyer School (historical) | School | 145 | Crawford | 38 55 24 N | 087 51 40 W |
| Moyers Cemetery | Cemetery | 136 | Franklin | 37 54 49 N | 089 07 21 W |
| Mozart Elementary School | School | 184 | Cook | 41 55 16 N | 087 43 20 W |
| Mozart Park | Park | 184 | Cook | 41 55 05 N | 087 43 24 W |
| Mozart School (historical) | School | 187 | Clark | 39 26 33 N | 087 44 40 W |
| Mozier | Populated Place | 135 | Calhoun | 39 17 33 N | 090 44 57 W |
| Mozier Hollow | Valley | | Calhoun | 39 15 38 N | 090 42 56 W |
| Mozier Hollow School (historical) | School | 163 | Calhoun | 39 15 51 N | 090 42 35 W |
| Mozier Landing | Populated Place | 133 | Calhoun | 39 15 20 N | 090 43 33 W |
| Mraz Park | Park | 188 | Cook | 41 50 54 N | 087 47 40 W |
| MSDGC Dam Number 3 | Dam | 191 | Fulton | 40 29 54 N | 090 09 12 W |
| MSDGC Dam Number 3 | Dam | 191 | Fulton | 40 31 00 N | 090 05 24 W |
| MSDGC Dam Number 5 | Dam | 190 | Fulton | 40 29 12 N | 090 09 54 W |
| MSDGC Dam Number 5 | Dam | 210 | Fulton | 39 27 30 N | 090 04 18 W |
| MSDGC Dam Number 6 | Dam | 190 | Fulton | 40 28 12 N | 090 10 36 W |
| MSDGC Dam Number 7 | Dam | 180 | Fulton | 40 28 24 N | 090 07 42 W |
| MSDGC Dam Number 7 | Dam | 191 | Fulton | 40 27 42 N | 090 10 30 W |
| MSDGC Dam Number 8 | Dam | 179 | Fulton | 40 29 42 N | 090 08 54 W |
| MSDGC Dam Number 9 | Dam | 175 | Fulton | 40 29 30 N | 090 09 00 W |
| Mud Acre School (historical) | School | 185 | McDonough | 40 19 18 N | 090 28 08 W |
| Mud Bridge | Bridge | 129 | Wayne | 38 29 16 N | 088 41 57 W |
| Mud College (historical) | School | 235 | Warren | 40 42 28 N | 090 41 28 W |
| Mud College School (historical) | School | 185 | La Salle | 41 18 35 N | 088 49 34 W |
| Mud Corners School (historical) | School | 224 | Warren | 40 49 29 N | 090 32 19 W |
| Mud Creek | Stream | | Adams | 40 11 12 N | 091 16 23 W |
| Mud Creek | Stream | | Boone | 42 15 36 N | 088 45 02 W |
| Mud Creek | Stream | | Edgar | 39 28 04 N | 087 35 46 W |
| Mud Creek | Stream | | Edwards | 38 16 57 N | 087 58 40 W |
| Mud Creek | Stream | | Hardin | 37 25 31 N | 088 22 48 W |
| Mud Creek | Stream | | Henry | 41 16 16 N | 090 24 06 W |
| Mud Creek | Stream | | Henry | 41 27 45 N | 090 21 22 W |
| Mud Creek | Stream | | Henry | 41 28 28 N | 089 59 27 W |
| Mud Creek | Stream | | Iroquois | 40 37 46 N | 087 43 26 W |
| Mud Creek | Stream | | Iroquois | 40 38 14 N | 087 35 19 W |
| Mud Creek | Stream | | Jackson | 37 46 18 N | 089 17 03 W |
| Mud Creek | Stream | | Livingston | 41 01 35 N | 088 47 03 W |
| Mud Creek | Stream | | Massac | 37 07 13 N | 088 36 18 W |
| Mud Creek | Stream | | Massac | 37 09 46 N | 088 42 53 W |
| Mud Creek | Stream | | McLean | 40 18 09 N | 089 01 23 W |
| Mud Creek | Stream | | Montgomery | 39 03 14 N | 089 17 14 W |
| Mud Creek | Stream | | Morgan | 39 52 18 N | 090 23 33 W |
| Mud Creek | Stream | | Ogle | 42 03 09 N | 089 20 49 W |
| Mud Creek | Stream | | Ogle | 42 07 50 N | 089 24 13 W |
| Mud Creek | Stream | | Rock Island | 41 22 39 N | 090 35 04 W |
| Mud Creek | Stream | | Shelby | 39 24 28 N | 088 53 45 W |
| Mud Creek | Stream | | St. Clair | 38 21 06 N | 089 47 54 W |
| Mud Creek | Stream | | Tazewell | 40 30 37 N | 089 24 58 W |
| Mud Creek | Stream | | Winnebago | 42 20 50 N | 089 04 30 W |
| Mud Creek School (historical) | School | 228 | Ogle | 42 08 14 N | 089 25 57 W |
| Mud Creek School (historical) | School | 204 | Will | 41 23 37 N | 087 58 12 W |
| Mud Island | Island | 149 | Adams | 40 11 46 N | 091 29 49 W |
| Mud Island | Island | 149 | Hancock | 40 22 32 N | 091 24 50 W |
| Mud Island School (historical) | School | 242 | Kane | 41 51 38 N | 088 29 23 W |
| Mud Lake | Lake | 234 | Cook | 42 09 06 N | 088 12 55 W |
| Mud Lake | Lake | 101 | Gallatin | 37 35 54 N | 088 09 50 W |
| Mud Lake | Lake | 225 | Lake | 42 26 20 N | 088 11 11 W |
| Mud Lake | Lake | 133 | Mason | 40 24 15 N | 089 57 06 W |
| Mud Lake | Lake | 170 | Sangamon | 39 50 56 N | 089 33 46 W |
| Mud Lane School (historical) | School | 187 | Livingston | 41 04 03 N | 088 52 35 W |
| Mud Run | Stream | | Jo Daviess | 42 25 29 N | 090 00 58 W |
| Mud Run | Stream | | Knox | 41 06 07 N | 090 08 06 W |
| Mud Run | Stream | | Stark | 41 00 28 N | 089 46 22 W |
| Mud Run Cemetery | Cemetery | 169 | Shelby | 39 14 46 N | 088 53 54 W |
| Mud Run School (historical) | School | 176 | Shelby | 39 14 47 N | 088 54 01 W |
| Mud School (historical) | School | 231 | Winnebago | 42 21 46 N | 089 14 18 W |
| Mud Slough | Gut | 133 | Calhoun | 39 08 22 N | 090 41 24 W |
| Mud Slough | Gut | 139 | Mason | 40 05 34 N | 090 06 02 W |
| Mud Slough | Gut | 133 | Pike | 39 25 46 N | 090 56 17 W |
| Mud Slough | Gut | 135 | Pike | 39 30 48 N | 091 03 21 W |
| Mud Slough | Stream | | Grundy | 41 21 03 N | 088 25 08 W |
| Mud Slough | Stream | | Jo Daviess | 42 19 53 N | 090 24 53 W |
| Mud Slough (historical) | Lake | 146 | Hancock | 40 16 21 N | 091 27 39 W |
| Mud Springs Hollow | Valley | | Saline | 37 38 10 N | 088 29 43 W |
| Mud Valley Church | Church | 193 | Schuyler | 40 10 54 N | 090 20 16 W |
| Mudds Landing | Locale | 116 | Randolph | 38 00 48 N | 090 03 15 W |
| Muddy | Populated Place | 113 | Saline | 37 45 54 N | 088 31 00 W |
| Muddy Church (historical) | Church | 104 | Pope | 37 09 08 N | 088 27 48 W |
| Muddy Creek | Stream | | Crawford | 39 03 12 N | 087 55 42 W |
| Muddy Creek | Stream | | Cumberland | 39 10 56 N | 088 13 51 W |
| Muddy Creek | Stream | | Fayette | 38 50 19 N | 089 13 18 W |
| Muddy Creek | Stream | | Fulton | 40 24 41 N | 090 15 51 W |
| Muddy Creek | Stream | | Lawrence | 38 46 34 N | 087 45 07 W |
| Muddy Creek | Stream | | Stephenson | 42 26 19 N | 089 44 24 W |
| Muddy Creek Ditch | Canal | 137 | Fayette | 38 49 53 N | 089 13 19 W |
| Muddy Lake | Lake | 119 | Washington | 38 26 08 N | 089 38 42 W |
| Muddy Lane School (historical) | School | 234 | McDonough | 40 35 19 N | 090 46 17 W |