County ProfileIL
St. Clair County
Population: 257,400 · 29 ZIP codes
Demographics
Source: U.S. Census Bureau (ACS/Decennial). Estimates vary by year.
People
Total population
257,400
People
Median age
39.9
Housing
Total households
100,846
Income
Median household income
$73,854
Housing
Total housing units
115,630
Employment
Employment rate
57.7%
Education
Bachelor’s degree or higher
31.8%
Healthcare
Insured population
94.9%
County details
Local time 02:14:03(CT)| Name | St. Clair |
|---|---|
| Total ZIP codes | 29total |
| ZIP codes (by type) | 24 Standard5 PO Box |
| Area code | 618, 730 |
| Timezone | Central Time (CT) |
| Coordinates | 38.4701976, -89.9285459 |
| Land area | 657.7 sq miles(1,703.6 km²) |
Map of St. Clair county, Illinois with ZIP codes
Cities and Communities in St. Clair County
Compare the largest cities in St. Clair County by population, median income, and growth. Use the table below to analyze key demographic shifts across the region.
| City | Population | Median incomeHousehold | ZIP codes |
|---|---|---|---|
| Belleville | 42,404 | $63,535 | 5ZIPs |
| O Fallon | 32,289 | $105,982 | 1ZIPs |
| East Saint Louis | 18,469 | $35,700 | 7ZIPs |
| Fairview Heights | 16,706 | $80,930 | 1ZIPs |
| Mascoutah | 8,754 | $97,375 | 1ZIPs |
| Scott Air Force Base | 5,332 | — | 1ZIPs |
| Lebanon | 4,691 | $88,750 | 1ZIPs |
| Freeburg | 4,582 | $92,065 | 1ZIPs |
| Caseyville | 4,400 | $60,669 | 1ZIPs |
| Millstadt | 4,071 | $90,901 | 1ZIPs |
| Smithton | 4,006 | $135,455 | 1ZIPs |
| Dupo | 3,996 | $61,644 | 1ZIPs |
| New Athens | 1,955 | $56,553 | 1ZIPs |
| Marissa | 1,833 | $54,814 | 1ZIPs |
| Lovejoy | 631 | — | 1ZIPs |
| Saint Libory | 628 | $116,964 | 1ZIPs |
| Lenzburg | 468 | $42,656 | 1ZIPs |
| East Carondelet | 390 | $67,500 | 1ZIPs |
| Summerfield | 347 | $51,944 | 1ZIPs |
— Data unavailable or suppressed by the U.S. Census Bureau for areas with small sample sizes to protect individual privacy.
ZIP Codes in St. Clair County
Review the most populated postal areas across St. Clair County. Use the ranking below to compare resident density and demographic scales between the county's major zones.
| ZIP | City | Median incomeHousehold | Population (ZIP) |
|---|---|---|---|
| 62269 | O Fallon | $103,818 | 36,068 |
| 62226 | Belleville | $70,797 | 29,156 |
| 62221 | Belleville | $82,271 | 29,039 |
| 62220 | Belleville | $65,952 | 19,474 |
| 62208 | Fairview Heights | $80,205 | 16,992 |
| 62223 | Belleville | $73,700 | 16,263 |
| 62206 | East Saint Louis | $33,838 | 12,929 |
| 62258 | Mascoutah | $94,655 | 10,379 |
| 62232 | Caseyville | $64,269 | 7,547 |
| 62260 | Millstadt | $91,039 | 7,162 |
| 62207 | East Saint Louis | $29,845 | 7,045 |
| 62205 | East Saint Louis | $45,672 | 6,682 |
| 62254 | Lebanon | $96,492 | 6,503 |
| 62203 | East Saint Louis | $42,111 | 6,344 |
| 62243 | Freeburg | $103,342 | 5,796 |
| 62225 | Scott Air Force Base | $103,284 | 5,332 |
| 62201 | East Saint Louis | $27,437 | 5,125 |
| 62285 | Smithton | $136,345 | 4,718 |
| 62239 | Dupo | $61,191 | 4,638 |
| 62204 | East Saint Louis | $35,346 | 4,483 |
Data Sources & Citations
The geographic and demographic information presented on this site is compiled from publicly available, authoritative sources, including:
- United States Census BureauDemographic, population, housing, and socioeconomic data sourced from Census Bureau datasets, including the Decennial Census and the American Community Survey (ACS).Census Data
- United States Postal Service (USPS)ZIP code classifications, delivery types, and postal designations used for reference purposes. USPS ZIP codes are intended for mail delivery and may not always align exactly with Census geographic boundaries.USPS