| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| Reader | city | Illinois | United States | 39.31 | -90.04 | 830 | |
| Reading | city | Illinois | United States | 41.07 | -88.85 | 830 | |
| Reardon | city | Illinois | United States | 39.12 | -90.58 | 830 | |
| Rectorville (historical) | city | Illinois | United States | 37.92 | -88.46 | 393 | |
| Red Bud | city | Illinois | United States | 38.21 | -89.99 | 830 | |
| Red Bud (historical) | city | Illinois | United States | 37.78 | -88.41 | 396 | |
| Red Haw Ridge | city | Illinois | United States | 42.13 | -87.81 | 830 | |
| Red Oak | city | Illinois | United States | 42.39 | -89.67 | 830 | |
| Red Top | city | Illinois | United States | 38.37 | -88.03 | 410 | |
| Reddick | city | Illinois | United States | 41.10 | -88.25 | 830 | |
| Reddish | city | Illinois | United States | 39.14 | -90.58 | 830 | |
| Redgate Ridge | city | Illinois | United States | 41.96 | -88.33 | 830 | |
| Redmon | city | Illinois | United States | 39.65 | -87.86 | 830 | |
| Reed Crossing | city | Illinois | United States | 41.27 | -88.83 | 830 | |
| Reeds | city | Illinois | United States | 40.92 | -90.83 | 830 | |
| Reeds Crossing (historical) | city | Illinois | United States | 42.20 | -88.80 | 830 | |
| Reeds Station | city | Illinois | United States | 37.78 | -89.16 | 416 | |
| Rees | city | Illinois | United States | 39.64 | -90.09 | 830 | |
| Reevesville | city | Illinois | United States | 37.34 | -88.72 | 354 | |
| Regal Acres | city | Illinois | United States | 41.59 | -88.00 | 830 | |
| Regency Place | city | Illinois | United States | 42.13 | -87.88 | 830 | |
| Reilly | city | Illinois | United States | 40.42 | -87.85 | 830 | |
| Reily Lake | city | Illinois | United States | 37.98 | -89.92 | 393 | |
| Renault | city | Illinois | United States | 38.15 | -90.13 | 830 | |
| Rend City | city | Illinois | United States | 38.03 | -88.98 | 393 | |
| Rennerville | city | Illinois | United States | 39.46 | -88.81 | 830 | |
| Reno | city | Illinois | United States | 38.98 | -89.51 | 830 | |
| Renshaw | city | Illinois | United States | 37.35 | -88.68 | 390 | |
| Rentchler | city | Illinois | United States | 38.49 | -89.87 | 830 | |
| Reserve of Plainfield | city | Illinois | United States | 41.63 | -88.17 | 830 | |
| Reserves at Clearwater | city | Illinois | United States | 41.71 | -88.21 | 830 | |
| Resthaven | city | Illinois | United States | 41.26 | -88.14 | 830 | |
| Reynolds | city | Illinois | United States | 41.33 | -90.67 | 830 | |
| Reynoldsburg | city | Illinois | United States | 37.52 | -88.78 | 830 | |
| Reynoldsville | city | Illinois | United States | 37.37 | -89.40 | 337 |