| ZIP Codes: | 8 ZIP Codes (8 Standard, 0 PO Box, 0 Unique) [See All] |
| Area Codes: | 319 / 641 |
| Timezone: | Central (GMT -06:00) |
| Local Time: | 11:53:12 PM |
| Population: | 19,220 [See All] |
| FIPS: | 19157 |
| Land Area: | 614 sq mi |
| Water Area: | 1 sq mi |
| Coordinates: | 41.6810, -92.4907 |
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19,220 residents live across 8 ZIPs covering 614 sq mi, served by 8 distinct USPS-recognized cities.
Population moved from 19,446 to 19,220 from 2014 to 2024 — a -1.2% change. 3 ZIPs gained residents, 5 lost.
The county's wealthiest ZIP 50157 (Malcom, $115,000 median) and poorest ZIP 50171 (Montezuma, $65,000) are 11.8 miles apart — a 1.8× income gap across local geography.
Median home values vary 1.9× across this county — from $120,500 in 52222 (Deep River) to $228,000 in 52221 (Guernsey).
Density varies 9× across the county — from 7 people/sq mi in 50157 (Malcom) to 64 in 50112 (Grinnell).
Educational attainment ranges from 10.2% bachelor's+ in 52221 (Guernsey) to 35.0% in 50112 (Grinnell) — the breadth of educational profiles across the area.
Within Iowa, this is the #34 most populous of 99 counties and ranks #22 for median household income .
Weighted by population, the typical household earns about $70,270 across the county — reflecting what a typical resident sees, not a simple ZIP average.
27.8% of adults age 25+ hold a bachelor's degree or higher (3,521 of 12,651 reporting).
8 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.
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 |
|---|---|---|---|---|---|---|
| 50112 | Grinnell | Standard | 11,862 | $67,078 | 184.4 | -0.1% |
| 52211 | Brooklyn | Standard | 2,795 | $73,922 | 91.6 | 11.8% |
| 50171 | Montezuma | Standard | 2,524 | $65,000 | 113.2 | -14.3% |
| 52222 | Deep River | Standard | 631 | $81,964 | 72.2 | -9.9% |
| 50157 | Malcom | Standard | 473 | $115,000 | 65.0 | -21.3% |
| 52221 | Guernsey | Standard | 332 | $86,473 | 22.0 | 64.4% |
| 50242 | Searsboro | Standard | 326 | $67,104 | 41.5 | -24.0% |
| 52232 | Hartwick | Standard | 277 | $99,391 | 23.9 | 42.8% |