| ZIP Codes: | 11 ZIP Codes (10 Standard, 1 PO Box, 0 Unique) [See All] |
| Area Code: | 641 |
| Timezone: | Central (GMT -06:00) |
| Local Time: | 2:11:51 PM |
| Population: | 42,331 [See All] |
| FIPS: | 19033 |
| CBSA: | Mason City, IA |
| Land Area: | 576 sq mi |
| Water Area: | 7 sq mi |
| Coordinates: | 43.0735, -93.2591 |
| Quick Link: |
42,331 residents live across 11 ZIPs covering 576 sq mi, served by 10 distinct USPS-recognized cities.
Population moved from 43,264 to 42,331 from 2014 to 2024 — a -2.2% change. 3 ZIPs gained residents, 7 lost.
The county's wealthiest ZIP 50482 (Ventura, $98,289 median) and poorest ZIP 50457 (Meservey, $47,250) are 14.5 miles apart — a 2.1× income gap across local geography.
Median home values vary 3.4× across this county — from $83,000 in 50477 (Swaledale) to $283,400 in 50428 (Clear Lake).
Density varies 17× across the county — from 11 people/sq mi in 50479 (Thornton) to 193 in 50401 (Mason City).
Educational attainment ranges from 7.8% bachelor's+ in 50464 (Plymouth) to 33.9% in 50482 (Ventura) — the breadth of educational profiles across the area.
Within Iowa, this is the #14 most populous of 99 counties and ranks #62 for median household income .
Weighted by population, the typical household earns about $70,218 across the county — reflecting what a typical resident sees, not a simple ZIP average.
23.8% of adults age 25+ hold a bachelor's degree or higher (7,259 of 30,491 reporting).
10 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.
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 |
|---|---|---|---|---|---|---|
| 50401 | Mason City | Standard | 28,703 | $66,072 | 148.5 | -2.1% |
| 50428 | Clear Lake | Standard | 9,071 | $81,037 | 123.8 | -2.0% |
| 50469 | Rockwell | Standard | 1,527 | $71,250 | 90.4 | -2.3% |
| 50482 | Ventura | Standard | 748 | $98,289 | 29.6 | -14.9% |
| 50464 | Plymouth | Standard | 694 | $91,750 | 26.6 | 4.0% |
| 50479 | Thornton | Standard | 655 | $68,750 | 57.4 | 21.3% |
| 50457 | Meservey | Standard | 463 | $47,250 | 32.4 | 35.4% |
| 50477 | Swaledale | Standard | 250 | $52,321 | 21.4 | -33.7% |
| 50433 | Dougherty | Standard | 157 | $69,167 | 44.8 | -32.9% |
| 50467 | Rock Falls | Standard | 63 | $63,750 | 1.4 | -26.7% |
| 50402 | Mason City | PO Box | — | — | 0.0 | — |