| Zip Code | Primary City | Secondary City | More Information |
| 61101 | Rockford | Rockford | Rockford population stats |
| 61103 | Rockford | Rockford | Rockford population stats |
| 61104 | Rockford | Rockford | Rockford population stats |
| 61105 | Rockford | Rockford | Rockford population stats |
| 61106 | Rockford | Rockford | Rockford population stats |
| 61107 | Rockford | Rockford | Rockford population stats |
| 61108 | Rockford | Rockford | Rockford population stats |
| 61109 | Rockford | Rockford | Rockford population stats |
| 61110 | Rockford | Rockford | Rockford population stats |
| 61112 | Rockford | Rockford | Rockford population stats |
| 61114 | Rockford | Rockford | Rockford population stats |
| 61125 | Rockford | Rockford | Rockford population stats |
| 61126 | Rockford | Rockford | Rockford population stats |