| ZIP Codes: | 11 ZIP Codes (11 Standard, 0 PO Box, 0 Unique) [See All] |
| Area Codes: | 618 / 730 |
| Timezone: | Central (GMT -06:00) |
| Local Time: | 2:12:02 PM |
| Population: | 42,808 [See All] |
| FIPS: | 17121 |
| CBSA: | Centralia, IL |
| Land Area: | 707 sq mi |
| Water Area: | 10 sq mi |
| Coordinates: | 38.6433, -88.9908 |
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42,808 residents live across 11 ZIPs covering 707 sq mi, served by 11 distinct USPS-recognized cities.
Population moved from 45,999 to 42,808 from 2014 to 2024 — a -6.9% change. 4 ZIPs gained residents, 7 lost.
The county's wealthiest ZIP 62807 (Alma, $82,321 median) and poorest ZIP 62801 (Centralia, $52,017) are 21.9 miles apart — a 1.6× income gap across local geography.
Median home values vary 2.0× across this county — from $79,900 in 62853 (Kell) to $158,500 in 62807 (Alma).
Density varies 10× across the county — from 14 people/sq mi in 62875 (Patoka) to 138 in 62801 (Centralia).
Educational attainment ranges from 7.9% bachelor's+ in 62882 (Sandoval) to 30.9% in 62807 (Alma) — the breadth of educational profiles across the area.
Within Illinois, this is the #34 most populous of 102 counties and ranks #79 for median household income .
Weighted by population, the typical household earns about $59,959 across the county — reflecting what a typical resident sees, not a simple ZIP average.
16.1% of adults age 25+ hold a bachelor's degree or higher (4,882 of 30,236 reporting).
11 Standard delivery, 0 PO Box only, 0 single-entity Unique ZIPs serve this county.
A frontier county — vast land area with only a few residents per square mile. Daily life looks very different here than in the country's denser counties.
Marion County lost 6.9% of residents between 2014 and 2024. ZIPs that shed the largest share:
| ZIP | City | Type | Population | Median Income | Area (sq mi) | 10-yr Growth |
|---|---|---|---|---|---|---|
| 62801 | Centralia | Standard | 19,827 | $52,017 | 143.3 | -11.6% |
| 62881 | Salem | Standard | 11,078 | $71,270 | 103.0 | -0.9% |
| 62870 | Odin | Standard | 2,281 | $59,821 | 39.6 | 23.0% |
| 62882 | Sandoval | Standard | 2,057 | $55,582 | 34.6 | -6.2% |
| 62849 | Iuka | Standard | 1,887 | $60,789 | 114.5 | -18.5% |
| 62854 | Kinmundy | Standard | 1,827 | $63,587 | 87.7 | 2.9% |
| 62875 | Patoka | Standard | 1,039 | $73,333 | 74.5 | -11.4% |
| 62853 | Kell | Standard | 969 | $60,721 | 25.9 | 2.8% |
| 62893 | Walnut Hill | Standard | 926 | $59,063 | 21.0 | 16.0% |
| 62807 | Alma | Standard | 767 | $82,321 | 40.9 | -25.1% |
| 62892 | Vernon | Standard | 150 | $75,417 | 22.2 | -51.0% |