| ZIP Codes: | 7 ZIP Codes (4 Standard, 3 PO Box, 0 Unique) [See All] |
| Area Codes: | 618 / 730 |
| Timezone: | Central (GMT -06:00) |
| Local Time: | 2:12:02 PM |
| Population: | 35,417 [See All] |
| FIPS: | 17133 |
| CBSA: | St. Louis, MO-IL |
| Land Area: | 334 sq mi |
| Water Area: | 12 sq mi |
| Coordinates: | 38.2695, -90.1757 |
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35,417 residents live across 7 ZIPs covering 334 sq mi, served by 7 distinct USPS-recognized cities.
Population moved from 32,434 to 35,382 from 2014 to 2024 — a +9.1% change. 4 ZIPs gained residents, 2 lost.
The county's wealthiest ZIP 62236 (Columbia, $108,981 median) and poorest ZIP 62248 (Hecker, $79,583) are 15.2 miles apart — a 1.4× income gap across local geography.
Median home values vary 1.8× across this county — from $166,800 in 62248 (Hecker) to $306,600 in 62236 (Columbia).
Density varies 121× across the county — from 17 people/sq mi in 62244 (Fults) to 2,034 in 62248 (Hecker).
Educational attainment ranges from 19.9% bachelor's+ in 62295 (Valmeyer) to 46.7% in 62236 (Columbia) — the breadth of educational profiles across the area.
Within Illinois, this is the #39 most populous of 102 counties and ranks #5 for median household income with the #2 fastest decade growth .
Weighted by population, the typical household earns about $103,745 across the county — reflecting what a typical resident sees, not a simple ZIP average.
39.0% of adults age 25+ hold a bachelor's degree or higher (9,869 of 25,285 reporting).
4 Standard delivery, 3 PO Box only, 0 single-entity Unique ZIPs serve this county.
| ZIP | City | Type | Population | Median Income | Area (sq mi) | 10-yr Growth |
|---|---|---|---|---|---|---|
| 62298 | Waterloo | Standard | 18,208 | $101,155 | 142.1 | 10.1% |
| 62236 | Columbia | Standard | 14,154 | $108,981 | 61.1 | 11.6% |
| 62295 | Valmeyer | Standard | 1,459 | $87,989 | 75.3 | -13.2% |
| 62244 | Fults | Standard | 928 | $107,917 | 55.2 | -21.0% |
| 62248 | Hecker | PO Box | 521 | $79,583 | 0.3 | 71.4% |
| 62279 | Renault | PO Box | 112 | $139,063 | 0.0 | 93.1% |
| 62256 | Maeystown | PO Box | 35 | $126,250 | 0.0 | — |