Zip Code | City | Population |
|---|---|---|
| 61108 | Rockford | 29,673 |
| 61107 | Rockford | 29,386 |
| 61109 | Rockford | 26,382 |
| 61103 | Rockford | 23,441 |
| 61111 | Loves Park | 22,756 |
| 61115 | Machesney Park | 22,542 |
| 61073 | Roscoe | 20,567 |
| 61101 | Rockford | 20,481 |
| 61104 | Rockford | 18,306 |
| 61102 | Rockford | 16,875 |
| 61114 | Rockford | 15,017 |
| 61072 | Rockton | 11,077 |
| 61080 | South Beloit | 10,780 |
| 61088 | Winnebago | 6,094 |
| 61016 | Cherry Valley | 5,185 |
| 61063 | Pecatonica | 4,144 |
| 61024 | Durand | 2,524 |
| 61079 | Shirland | 213 |
| 61077 | Seward | 118 |
| 61112 | Rockford | 113 |