| ZIP Codes: | 12 ZIP Codes (11 Standard, 1 PO Box, 0 Unique) [See All] |
| Area Codes: | 309 / 779 / 815 / 861 |
| Timezone: | Central (GMT -06:00) |
| Local Time: | 2:12:04 PM |
| Population: | 56,250 [See All] |
| FIPS: | 17195 |
| CBSA: | Sterling, IL |
| Land Area: | 804 sq mi |
| Water Area: | 13 sq mi |
| Coordinates: | 41.7223, -89.9165 |
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56,250 residents live across 12 ZIPs covering 804 sq mi, served by 12 distinct USPS-recognized cities.
Population moved from 58,734 to 56,250 from 2014 to 2024 — a -4.2% change. 3 ZIPs gained residents, 9 lost.
The county's wealthiest ZIP 61250 (Erie, $84,688 median) and poorest ZIP 61252 (Fulton, $59,861) are 12.9 miles apart — a 1.4× income gap across local geography.
Median home values vary 1.9× across this county — from $102,300 in 61071 (Rock Falls) to $190,900 in 61251 (Fenton).
Density varies 12× across the county — from 16 people/sq mi in 61283 (Tampico) to 180 in 61071 (Rock Falls).
Educational attainment ranges from 10.8% bachelor's+ in 61283 (Tampico) to 25.7% in 61270 (Morrison) — the breadth of educational profiles across the area.
Within Illinois, this is the #24 most populous of 102 counties and ranks #38 for median household income .
Weighted by population, the typical household earns about $67,854 across the county — reflecting what a typical resident sees, not a simple ZIP average.
20.4% of adults age 25+ hold a bachelor's degree or higher (8,076 of 39,586 reporting).
11 Standard delivery, 1 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 |
|---|---|---|---|---|---|---|
| 61081 | Sterling | Standard | 20,844 | $67,586 | 124.2 | -3.6% |
| 61071 | Rock Falls | Standard | 13,581 | $60,508 | 75.6 | -5.7% |
| 61270 | Morrison | Standard | 6,912 | $80,867 | 152.6 | -0.9% |
| 61252 | Fulton | Standard | 5,437 | $59,861 | 63.1 | 2.9% |
| 61277 | Prophetstown | Standard | 3,054 | $70,363 | 139.5 | -1.3% |
| 61250 | Erie | Standard | 2,781 | $84,688 | 82.7 | 8.0% |
| 61283 | Tampico | Standard | 1,269 | $64,063 | 81.4 | -14.8% |
| 61230 | Albany | Standard | 1,039 | $62,344 | 21.1 | -28.7% |
| 61261 | Lyndon | Standard | 656 | $64,375 | 16.5 | -35.9% |
| 61251 | Fenton | Standard | 377 | $79,464 | 17.7 | 22.4% |
| 61243 | Deer Grove | Standard | 155 | $148,309 | 29.7 | -33.8% |
| 61037 | Galt | PO Box | 145 | $70,357 | 0.0 | -48.4% |