Illinois ZIP codes
Illinois holds 1,575 ZIP codes between 60001 and 62999. The tables rank the places and counties with the most codes; the guide below decodes the numbering.
Places with the most ZIP codes in Illinois
| Place | ZIP codes |
|---|---|
| Chicago | 84 |
| Springfield | 35 |
| Peoria | 29 |
| Rockford | 14 |
| Aurora | 10 |
| Bloomington | 8 |
| Palatine | 7 |
| Schaumburg | 7 |
| East Saint Louis | 7 |
| Champaign | 6 |
| Evanston | 6 |
| Carol Stream | 6 |
| Naperville | 6 |
| Decatur | 6 |
| Joliet | 6 |
| Elgin | 5 |
| Belleville | 5 |
| Des Plaines | 4 |
| Oak Park | 4 |
| Loves Park | 4 |
Illinois counties by ZIP count
| County | ZIP codes |
|---|---|
| Cook | 213 |
| Sangamon | 54 |
| DuPage | 53 |
| Peoria | 44 |
| Champaign | 33 |
| Lake | 33 |
| Will | 33 |
| McLean | 32 |
| St. Clair | 30 |
| Kane | 29 |
Reading a Illinois ZIP code
Illinois holds 1,575 ZIP codes between 60001 and 62999, spread over 102 counties. Chicago leads the state with 84 codes, ahead of Springfield with 35. Every code here opens with the digit 6: that opening number is the national postal region Illinois belongs to, the next two digits name the sectional center that sorts the mail, and the final two point to the local office. A ZIP+4 suffix narrows delivery to a block face. Boundaries follow carrier routes rather than city limits, which is why Chicago spreads across 84 codes while some rural codes cross county lines.
Source: GeoNames postal dataset (CC BY 4.0), snapshot of 2026-07-09. Counts cover standard delivery ZIPs listed for Illinois; unique and PO box codes may add to these totals.
Last updated: · Methodology and sources