Zip Code | City | Population |
|---|---|---|
| 61350 | Ottawa | 24,385 |
| 61364 | Streator | 18,245 |
| 61354 | Peru | 10,422 |
| 61301 | La Salle | 10,380 |
| 61342 | Mendota | 8,389 |
| 61341 | Marseilles | 7,196 |
| 60551 | Sheridan | 4,850 |
| 61348 | Oglesby | 4,501 |
| 60518 | Earlville | 3,514 |
| 61360 | Seneca | 3,379 |
| 60531 | Leland | 2,269 |
| 61373 | Utica | 2,117 |
| 61377 | Wenona | 1,469 |
| 61370 | Tonica | 1,168 |
| 61325 | Grand Ridge | 1,028 |
| 60549 | Serena | 691 |
| 61334 | Lostant | 604 |
| 60537 | Millington | 551 |
| 60470 | Ransom | 387 |
| 61358 | Rutland | 374 |
| 61321 | Dana | 312 |
| 61372 | Troy Grove | 269 |
| 60557 | Wedron | 218 |
| 61316 | Cedar Point | 196 |
| 61332 | Leonore | 139 |
| 61371 | Triumph | 85 |