20 zips
| Zip Code | City | Population ↓ |
|---|---|---|
| 61108 | Rockford | 30,202 |
| 61107 | Rockford | 29,473 |
| 61109 | Rockford | 26,714 |
| 61103 | Rockford | 23,238 |
| 61111 | Loves Park | 22,838 |
| 61115 | Machesney Park | 22,424 |
| 61073 | Roscoe | 20,008 |
| 61101 | Rockford | 19,671 |
| 61104 | Rockford | 17,584 |
| 61102 | Rockford | 16,620 |
| 61114 | Rockford | 15,026 |
| 61072 | Rockton | 11,342 |
| 61080 | South Beloit | 11,062 |
| 61088 | Winnebago | 5,992 |
| 61016 | Cherry Valley | 5,166 |
| 61063 | Pecatonica | 4,257 |
| 61024 | Durand | 2,264 |
| 61079 | Shirland | 220 |
| 61112 | Rockford | 116 |
| 61077 | Seward | 101 |
The data shown reflect ZCTAs from the US Census. As of 2024, there are 20 ZCTAs in Winnebago County, Illinois (US Census).