| ZIP Codes: | 8 ZIP Codes (6 Standard, 2 PO Box, 0 Unique) [See All] |
| Area Code: | 563 |
| Timezone: | Central (GMT -06:00) |
| Local Time: | 2:11:55 PM |
| Population: | 19,199 [See All] |
| FIPS: | 19191 |
| Land Area: | 621 sq mi |
| Water Area: | 0 sq mi |
| Coordinates: | 43.2277, -91.8402 |
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19,199 residents live across 8 ZIPs covering 621 sq mi, served by 8 distinct USPS-recognized cities.
Population moved from 20,092 to 19,199 from 2014 to 2024 — a -4.4% change. 4 ZIPs gained residents, 3 lost.
The county's wealthiest ZIP 52132 (Calmar, $100,559 median) and poorest ZIP 52168 (Spillville, $54,375) are 3.6 miles apart — a 1.8× income gap across local geography.
Median home values vary 1.9× across this county — from $157,500 in 52168 (Spillville) to $292,200 in 52165 (Ridgeway).
Density varies 62× across the county — from 15 people/sq mi in 52144 (Fort Atkinson) to 907 in 52168 (Spillville).
Educational attainment ranges from 11.3% bachelor's+ in 52133 (Castalia) to 37.8% in 52101 (Decorah) — the breadth of educational profiles across the area.
Within Iowa, this is the #35 most populous of 99 counties and ranks #24 for median household income .
Weighted by population, the typical household earns about $78,150 across the county — reflecting what a typical resident sees, not a simple ZIP average.
32.2% of adults age 25+ hold a bachelor's degree or higher (4,154 of 12,882 reporting).
6 Standard delivery, 2 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.
One ZIP holds the majority of this county's population — a sign of a county built around a single city or town.
| ZIP | City | Type | Population | Median Income | Area (sq mi) | 10-yr Growth |
|---|---|---|---|---|---|---|
| 52101 | Decorah | Standard | 12,706 | $73,484 | 322.3 | -7.9% |
| 52132 | Calmar | Standard | 1,759 | $100,559 | 63.0 | -6.8% |
| 52161 | Ossian | Standard | 1,532 | $87,870 | 50.5 | 4.0% |
| 52165 | Ridgeway | Standard | 1,098 | $85,227 | 67.4 | 28.7% |
| 52144 | Fort Atkinson | Standard | 1,075 | $84,609 | 73.6 | -16.7% |
| 52133 | Castalia | Standard | 673 | $76,250 | 43.8 | 13.7% |
| 52168 | Spillville | PO Box | 356 | $54,375 | 0.4 | 85.4% |
| 52149 | Highlandville | PO Box | — | — | 0.0 | — |