| ZIP Codes: | 24 ZIP Codes (15 Standard, 9 PO Box, 0 Unique) [See All] |
| Area Codes: | 309 / 779 / 815 / 861 |
| Timezone: | Central (GMT -06:00) |
| Local Time: | 11:53:16 PM |
| Population: | 32,718 [See All] |
| FIPS: | 17011 |
| CBSA: | Ottawa, IL |
| Land Area: | 825 sq mi |
| Water Area: | 5 sq mi |
| Coordinates: | 41.4121, -89.4509 |
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32,718 residents live across 24 ZIPs covering 825 sq mi, served by 24 distinct USPS-recognized cities.
Population moved from 34,012 to 32,718 from 2014 to 2024 — a -3.8% change. 11 ZIPs gained residents, 13 lost.
The county's wealthiest ZIP 61361 (Sheffield, $91,250 median) and poorest ZIP 61344 (Mineral, $44,063) are 4.9 miles apart — a 2.1× income gap across local geography.
Median home values vary 3.0× across this county — from $54,800 in 61315 (Bureau) to $161,700 in 61320 (Dalzell).
Density varies 207× across the county — from 8 people/sq mi in 61344 (Mineral) to 1,566 in 61317 (Cherry).
Educational attainment ranges from 4.6% bachelor's+ in 61344 (Mineral) to 28.5% in 61356 (Princeton) — the breadth of educational profiles across the area.
Within Illinois, this is the #44 most populous of 102 counties and ranks #75 for median household income .
Weighted by population, the typical household earns about $69,684 across the county — reflecting what a typical resident sees, not a simple ZIP average.
21.6% of adults age 25+ hold a bachelor's degree or higher (5,058 of 23,397 reporting).
15 Standard delivery, 9 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.
| ZIP | City | Type | Population | Median Income | Area (sq mi) | 10-yr Growth |
|---|---|---|---|---|---|---|
| 61356 | Princeton | Standard | 10,799 | $68,243 | 183.5 | -0.4% |
| 61362 | Spring Valley | Standard | 5,764 | $71,558 | 27.5 | 1.6% |
| 61376 | Walnut | Standard | 1,894 | $61,200 | 97.8 | -26.6% |
| 61322 | Depue | PO Box | 1,530 | $65,795 | 3.7 | -5.3% |
| 61361 | Sheffield | Standard | 1,417 | $91,250 | 74.9 | 9.4% |
| 61329 | Ladd | Standard | 1,356 | $67,321 | 1.0 | 4.3% |
| 61368 | Tiskilwa | Standard | 1,273 | $88,214 | 76.8 | -8.9% |
| 61379 | Wyanet | Standard | 1,260 | $63,750 | 40.5 | -24.1% |
| 61330 | La Moille | Standard | 1,182 | $69,005 | 71.2 | -15.0% |
| 61349 | Ohio | Standard | 1,151 | $71,375 | 62.9 | 31.8% |
| 61345 | Neponset | Standard | 770 | $76,250 | 50.0 | -4.5% |
| 61320 | Dalzell | Standard | 727 | $76,250 | 0.9 | 1.1% |
| 61314 | Buda | Standard | 686 | $52,039 | 49.5 | -19.5% |
| 61337 | Malden | Standard | 558 | $78,571 | 7.6 | 4.5% |
| 61317 | Cherry | PO Box | 521 | $58,750 | 0.3 | 14.5% |
| 61312 | Arlington | Standard | 392 | $80,714 | 32.3 | -23.1% |
| 61359 | Seatonville | PO Box | 369 | $52,857 | 0.5 | 12.2% |
| 61338 | Manlius | PO Box | 299 | $75,750 | 0.3 | -9.4% |
| 61344 | Mineral | Standard | 264 | $44,063 | 35.0 | -8.3% |
| 61315 | Bureau | PO Box | 264 | $56,538 | 3.8 | 11.4% |
| 61323 | Dover | PO Box | 125 | $47,500 | 0.1 | 9.6% |
| 61374 | Van Orin | PO Box | 56 | $59,432 | 2.8 | -56.6% |
| 61346 | New Bedford | PO Box | 43 | $42,500 | 0.9 | -41.1% |
| 61328 | Kasbeer | PO Box | 18 | — | 1.5 | 28.6% |