Identifiers: city · village · CDP
| Rank | Community | Population |
|---|---|---|
| 1 | Rockford (city), IL | 148,655 |
| 2 | Belvidere (city), IL | 25,339 |
| 3 | Loves Park (city), IL | 23,397 |
| 4 | Machesney Park (village), IL | 22,950 |
| 5 | Roscoe (village), IL | 10,983 |
| 6 | South Beloit (city), IL | 7,989 |
| 7 | Rockton (village), IL | 7,863 |
| 8 | Candlewick Lake (CDP), IL | 5,115 |
| 9 | Poplar Grove (village), IL | 5,049 |
| 10 | Cherry Valley (village), IL | 2,905 |
| 11 | Capron (village), IL | 1,395 |
| 12 | Durand (village), IL | 1,390 |
| 13 | Timberlane (village), IL | 906 |
| 14 | New Milford (village), IL | 794 |
| 15 | Davis (village), IL | 589 |
| 16 | Monroe Center (village), IL | 411 |
| 17 | Argyle (CDP), IL | 332 |
| 18 | Chemung (CDP), IL | 276 |
| 19 | Caledonia (village), IL | 183 |