| ZIP Codes: | 7 ZIP Codes (7 Standard, 0 PO Box, 0 Unique) [See All] |
| Area Codes: | 779 / 815 |
| Timezone: | Central (GMT -06:00) |
| Local Time: | 2:11:59 PM |
| Population: | 16,069 [See All] |
| FIPS: | 17015 |
| Land Area: | 501 sq mi |
| Water Area: | 22 sq mi |
| Coordinates: | 42.0671, -89.9183 |
| Quick Link: |
16,069 residents live across 7 ZIPs covering 501 sq mi, served by 7 distinct USPS-recognized cities.
Population moved from 15,740 to 16,069 from 2014 to 2024 — a +2.1% change. 2 ZIPs gained residents, 5 lost.
The county's wealthiest ZIP 61046 (Lanark, $79,398 median) and poorest ZIP 61074 (Savanna, $50,691) are 15.3 miles apart — a 1.6× income gap across local geography.
Median home values vary 1.9× across this county — from $91,500 in 61074 (Savanna) to $173,100 in 61285 (Thomson).
Density varies 3× across the county — from 17 people/sq mi in 61014 (Chadwick) to 47 in 61074 (Savanna).
Educational attainment ranges from 10.4% bachelor's+ in 61285 (Thomson) to 25.8% in 61046 (Lanark) — the breadth of educational profiles across the area.
Within Illinois, this is the #64 most populous of 102 counties and ranks #72 for median household income .
Weighted by population, the typical household earns about $64,895 across the county — reflecting what a typical resident sees, not a simple ZIP average.
17.6% of adults age 25+ hold a bachelor's degree or higher (2,092 of 11,876 reporting).
7 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.
| ZIP | City | Type | Population | Median Income | Area (sq mi) | 10-yr Growth |
|---|---|---|---|---|---|---|
| 61074 | Savanna | Standard | 3,962 | $50,691 | 84.5 | -7.6% |
| 61046 | Lanark | Standard | 2,794 | $79,398 | 82.8 | -2.1% |
| 61285 | Thomson | Standard | 2,728 | $68,500 | 59.4 | 74.2% |
| 61053 | Mount Carroll | Standard | 2,590 | $62,250 | 103.2 | -12.5% |
| 61051 | Milledgeville | Standard | 1,469 | $59,565 | 50.9 | -6.3% |
| 61078 | Shannon | Standard | 1,459 | $75,769 | 56.9 | 9.1% |
| 61014 | Chadwick | Standard | 1,067 | $69,329 | 63.9 | -8.7% |