20 ZIP Codes
| Zip Code | City | Population ↓ |
|---|---|---|
| 61107 | Rockford | 30,765 |
| 61108 | Rockford | 30,355 |
| 61109 | Rockford | 26,768 |
| 61111 | Loves Park | 23,286 |
| 61103 | Rockford | 22,869 |
| 61115 | Machesney Park | 22,364 |
| 61073 | Roscoe | 20,194 |
| 61101 | Rockford | 19,318 |
| 61104 | Rockford | 17,222 |
| 61102 | Rockford | 15,937 |
| 61114 | Rockford | 15,325 |
| 61072 | Rockton | 11,285 |
| 61080 | South Beloit | 10,955 |
| 61088 | Winnebago | 6,167 |
| 61016 | Cherry Valley | 5,465 |
| 61063 | Pecatonica | 4,011 |
| 61024 | Durand | 2,318 |
| 61079 | Shirland | 210 |
| 61112 | Rockford | 152 |
| 61077 | Seward | 97 |
The data shown reflect ZCTAs from the US Census. As of 2025, there are 20 ZCTAs in Winnebago County, Illinois (US Census).