ZIP Codes of Union County, IA

Population & People
Population & People
Total Population
12,491
Household Income
Household Income
Median Income
$65,831
Housing
Housing
Total Housing Units
5,909
Business & Economy
Business & Economy
Total Businesses
305
Employment
Employment
Employment Rate
55.96%
Education
Education
Bachelor's Degree+
23.65%
Source: U.S. Census ACS 2024 5-Year Estimates · rolled up across the 7 ZIPs in this county.
Data Last Updated: June 1, 2026
ZIP Codes:7 ZIP Codes (6 Standard, 1 PO Box, 0 Unique) [See All]
Area Code:641
Timezone:Central (GMT -06:00)
Local Time:2:11:55 PM
Population:12,491 [See All]
FIPS:19175
Land Area:503 sq mi
Water Area:2 sq mi
Coordinates:41.0178, -94.2362
Quick Link:
https://www.zip-codes.com/county/ia-union.asp
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Extreme geographic sprawl
The largest ZIP spans 344× the smallest by area — 216.2 sq mi down to 0.63.

Standout ZIPs in this County


Most Populous
Creston · 9,034 people
72.3% of county total
Highest Income
Thayer · $64,211 median
1.0× county average
Largest Land Area
Creston · 216.2 sq mi
Spans the most ground
Fastest Growth
Afton · 1.8% (10-yr)
1,814 → 1,846 residents
Most Educated
Creston · 25.8% bachelor's+
1,555 of 6,018 adults 25+

Things worth knowing about Union County


12,491 residents live across 7 ZIPs covering 503 sq mi, served by 7 distinct USPS-recognized cities.

Population moved from 13,001 to 12,469 from 2014 to 2024 — a -4.1% change. 3 ZIPs gained residents, 3 lost.

The county's wealthiest ZIP 50254 (Thayer, $64,211 median) and poorest ZIP 50801 (Creston, $58,015) are 18.0 miles apart — a 1.1× income gap across local geography.

Median home values vary 1.7× across this county — from $104,700 in 50842 (Cromwell) to $175,000 in 50254 (Thayer).

Density varies 25× across the county — from 6 people/sq mi in 50254 (Thayer) to 158 in 50842 (Cromwell).

Educational attainment ranges from 11.0% bachelor's+ in 50842 (Cromwell) to 26.8% in 50861 (Shannon City) — the breadth of educational profiles across the area.

Within Iowa, this is the #61 most populous of 99 counties and ranks #87 for median household income .

Weighted by population, the typical household earns about $58,904 across the county — reflecting what a typical resident sees, not a simple ZIP average.

23.6% of adults age 25+ hold a bachelor's degree or higher (1,987 of 8,403 reporting).

6 Standard delivery, 1 PO Box only, 0 single-entity Unique ZIPs serve this county.

Stories about Union County


Big & sparse

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.

Total area
503
square miles
Avg density
24.8
people per sq mi
Population
12,491
across 7 ZIPs
Creston
216.2 sq mi
9,034 residents
Afton
118.0 sq mi
1,846 residents
Lorimor
79.2 sq mi
883 residents

Single-ZIP anchor

One ZIP holds the majority of this county's population — a sign of a county built around a single city or town.

Creston

All ZIP Codes in Union County


ZIPCityTypePopulationMedian IncomeArea (sq mi)10-yr Growth
50801CrestonStandard9,034$58,015216.2-5.3%
50830AftonStandard1,846$61,094118.01.8%
50149LorimorStandard883$59,16779.2-8.8%
50861Shannon CityStandard311$63,12541.7-1.0%
50254ThayerStandard296$64,21147.37.2%
50842CromwellStandard99$59,5830.616.5%
50831ArispePO Box22$95,6250.1

Adjacent & Nearby Counties