| Name | What | Region | Country | Lat | Long | Elev Ft. | Pop Est |
| Reader | city | Illinois | United States | 39.30556 | -90.04083 | 551 | 754 |
| Reading | city | Illinois | United States | 41.06667 | -88.85417 | 620 | 7707 |
| Reardon | city | Illinois | United States | 39.11583 | -90.575 | 429 | 1888 |
| Rectorville historical | city | Illinois | United States | 37.92167 | -88.45778 | 393 | 656 |
| Red Bud | city | Illinois | United States | 38.21167 | -89.99417 | 449 | 3026 |
| Red Bud historical | city | Illinois | United States | 37.77583 | -88.40528 | 396 | 3244 |
| Red Oak | city | Illinois | United States | 42.39222 | -89.67167 | 780 | 1786 |
| Red Top | city | Illinois | United States | 38.37194 | -88.02611 | 410 | 2576 |
| Reddick | city | Illinois | United States | 41.09722 | -88.25056 | 600 | 2224 |
| Reddish | city | Illinois | United States | 39.13778 | -90.57667 | 429 | 1810 |
| Redmon | city | Illinois | United States | 39.64528 | -87.86167 | 675 | 532 |
| Reed Crossing | city | Illinois | United States | 41.27361 | -88.83167 | 603 | 3755 |
| Reeds | city | Illinois | United States | 40.91722 | -90.82528 | 721 | 1070 |
| Reeds Crossing historical | city | Illinois | United States | 42.20139 | -88.79861 | 836 | 6925 |
| Reeds Station | city | Illinois | United States | 37.77778 | -89.16083 | 416 | 11782 |
| Rees | city | Illinois | United States | 39.63556 | -90.0925 | 692 | 1096 |
| Reevesville | city | Illinois | United States | 37.34306 | -88.71972 | 354 | 1361 |
| Reilly | city | Illinois | United States | 40.41583 | -87.85444 | 751 | 859 |
| Reily Lake | city | Illinois | United States | 37.97917 | -89.92083 | 498 | 2138 |
| Renault | city | Illinois | United States | 38.15361 | -90.13389 | 685 | 1252 |
| Rend City | city | Illinois | United States | 38.02694 | -88.98472 | 393 | 6204 |
| Rennerville | city | Illinois | United States | 39.45667 | -88.80722 | 695 | 5672 |
| Reno | city | Illinois | United States | 38.975 | -89.51389 | 561 | 1338 |
| Renshaw | city | Illinois | United States | 37.35444 | -88.67833 | 390 | 1028 |
| Rentchler | city | Illinois | United States | 38.49139 | -89.87306 | 459 | 8358 |
| Resthaven | city | Illinois | United States | 41.26194 | -88.13611 | 557 | 4973 |
| Reynolds | city | Illinois | United States | 41.32972 | -90.67028 | 800 | 1562 |
| Reynoldsburg | city | Illinois | United States | 37.51528 | -88.77583 | 528 | 1935 |
| Reynoldsville | city | Illinois | United States | 37.36722 | -89.395 | 337 | 1294 |
|
|