ZIP codes in St. Clair County, Illinois
St. Clair County has 34 ZIP codes. 23 lie entirely inside it and 11 are shared with neighboring counties, so part of their land and their people are elsewhere. About 256,183 people live in the parts inside it (ACS 2020–2024).
By the All Map Tools Team
- ZIP codes
- 34
- With 1% or more of their land inside
- Entirely inside
- 23
- 99% or more of their land
- Shared with other counties
- 11
- Most with Madison County (6)
- Most populated ZIP
- 62269
- 35,923 people · O'Fallon
- Least populated ZIP
- 62289
- 273 people · Summerfield
- Largest ZIP by land
- 62257
- 80 sq mi · Marissa
Map of the ZIP codes in St. Clair County
- Entirely in the county (99% or more of its land)
- Shared, mostly in this county
- Shared, mostly in other counties
- Neighboring counties
Each area is a ZIP code with its number where it fits. Hover over one to see its name.
All ZIP codes in St. Clair County
| ZIP code | Main city | Population | Land in the county | Residents in the county |
|---|---|---|---|---|
| 62059 | Brooklyn | 729 | 100% | 729 |
| 62060 | Madison | 3,558 | 4.9% | ≈ 42 |
| 62201 | Fairmont City | 4,921 | 96% | ≈ 4,835 |
| 62203 | East St. Louis | 5,465 | 100% | 5,465 |
| 62204 | Washington Park | 4,055 | 100% | 4,055 |
| 62205 | East St. Louis | 6,459 | 100% | 6,459 |
| 62206 | Cahokia | 12,959 | 100% | 12,959 |
| 62207 | Centreville | 6,984 | 100% | 6,984 |
| 62208 | Fairview Heights | 16,821 | 100% | 16,821 |
| 62220 | Belleville | 19,152 | 100% | 19,152 |
| 62221 | Shiloh | 29,875 | 100% | 29,875 |
| 62223 | Belleville | 16,269 | 100% | 16,269 |
| 62225 | Scott AFB | 5,242 | 100% | 5,242 |
| 62226 | Swansea | 28,255 | 100% | 28,255 |
| 62232 | Caseyville | 7,063 | 100% | 7,063 |
| 62234 | Collinsville | 31,648 | 17% | ≈ 3,817 |
| 62236 | Columbia | 14,154 | 18% | ≈ 1,288 |
| 62239 | Dupo | 4,232 | 100% | 4,232 |
| 62240 | Dupo | 1,796 | 100% | 1,796 |
| 62243 | Freeburg | 6,418 | 100% | 6,418 |
| 62254 | Lebanon | 6,710 | 98% | ≈ 6,536 |
| 62255 | Lenzburg | 1,092 | 100% | 1,092 |
| 62257 | Marissa | 2,046 | 57% | ≈ 1,462 |
| 62258 | Mascoutah | 10,437 | 100% | 10,437 |
| 62260 | Millstadt | 6,668 | 100% | 6,668 |
| 62264 | New Athens | 3,097 | 94% | ≈ 3,055 |
| 62265 | New Baden | 4,555 | 14% | ≈ 846 |
| 62269 | O'Fallon | 35,923 | 100% | 35,923 |
| 62282 | St. Libory | 563 | 100% | 563 |
| 62285 | Smithton | 4,239 | 100% | 4,239 |
| 62289 | Summerfield | 273 | 100% | 273 |
| 62293 | Trenton | 4,433 | 37% | ≈ 1,400 |
| 62294 | Troy | 15,325 | 2.8% | ≈ 171 |
| 62298 | Waterloo | 18,208 | 9.1% | ≈ 1,762 |
ZIP codes shared with other counties
These 11 ZIP codes have part of their land in another county. The first figure is the share of their land in St. Clair County; then, where the rest lies.
- 62060 (Madison): 4.9% here; 95% in Madison County.
- 62201 (Fairmont City): 96% here; 4.0% in Madison County.
- 62234 (Collinsville): 17% here; 83% in Madison County.
- 62236 (Columbia): 18% here; 82% in Monroe County.
- 62254 (Lebanon): 98% here; 1.7% in Madison County.
- 62257 (Marissa): 57% here; 36% in Washington County and 7.0% in Randolph County.
- 62264 (New Athens): 94% here; 5.6% in Monroe County.
- 62265 (New Baden): 14% here; 86% in Clinton County.
- 62293 (Trenton): 37% here; 46% in Clinton County and 16% in Madison County.
- 62294 (Troy): 2.8% here; 97% in Madison County.
- 62298 (Waterloo): 9.1% here; 91% in Monroe County.
Cities and prefixes
By main city (the city, town or CDP each ZIP shares the most land with), the ones with the most are Belleville (2), Dupo (2), East St. Louis (2), Brooklyn (1), Cahokia (1), and Caseyville (1); 31 places in all.
They start with 2 different three-digit prefixes, one per USPS sorting center: 620 and 622.
Neighboring counties
Each one with its ZIP codes. Those without a page of their own open in the tool.
Tools for this county
Sources
- U.S. Census Bureau, 2020 ZCTA to County, ZCTA to Place and ZCTA to Census Tract Relationship Files (and the 2022 County Subdivision to ZCTA file for Connecticut). Public domain.
- U.S. Census Bureau, American Community Survey 2020–2024 5-year estimates, table B01003 (population of each ZIP code, census tract and Connecticut town). Public domain.
- U.S. Census Bureau, Vintage 2025 Population Estimates (county population) and 2025 Gazetteer Files (land area and interior point of each ZIP code). Public domain.
- U.S. Census Bureau, Cartographic Boundary Files: ZCTAs 2020 and counties 2025, 1:500,000; county adjacency file 2025. Public domain.
How we count. ZIP codes here are the Census Bureau’s ZIP Code Tabulation Areas (ZCTAs), the areas it draws to match USPS ZIP codes; ZIPs with no area of their own (PO boxes, single buildings) aren’t included. A ZIP can cross county lines: “Land in the county” is the exact share of its land inside, from the Census relationship files. “Residents in the county” is the whole ZIP for those entirely inside; for shared ones it’s an estimate, spreading the people of each census tract over the land it shares with the ZIP. Population: ACS 2020–2024. Methodology.
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