ZIP Codes of Monona County, IA

Population & People
Population & People
Total Population
8,715
Household Income
Household Income
Median Income
$71,219
Housing
Housing
Total Housing Units
4,337
Business & Economy
Business & Economy
Total Businesses
226
Employment
Employment
Employment Rate
60.78%
Education
Education
Bachelor's Degree+
19.83%
Source: U.S. Census ACS 2024 5-Year Estimates · rolled up across the 9 ZIPs in this county.
Data Last Updated: June 1, 2026
ZIP Codes:9 ZIP Codes (9 Standard, 0 PO Box, 0 Unique) [See All]
Area Code:712
Timezone:Central (GMT -06:00)
Local Time:2:11:54 PM
Population:8,715 [See All]
FIPS:19133
Land Area:646 sq mi
Water Area:4 sq mi
Coordinates:42.0536, -95.9198
Quick Link:
https://www.zip-codes.com/county/ia-monona.asp
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Iowa's #84 most populous county
8,715 residents across 9 ZIPs — #84 of 99 Iowa counties.

Standout ZIPs in this County


Most Populous
Onawa · 3,500 people
40.2% of county total
Highest Income
Castana · $89,063 median
1.3× county average
Largest Land Area
Onawa · 143.8 sq mi
Spans the most ground
Fastest Growth
Onawa · -2.1% (10-yr)
3,576 → 3,500 residents
Most Educated
Mapleton · 21.8% bachelor's+
264 of 1,210 adults 25+

Things worth knowing about Monona County


8,715 residents live across 9 ZIPs covering 646 sq mi, served by 9 distinct USPS-recognized cities.

Population moved from 9,038 to 8,715 from 2014 to 2024 — a -3.6% change. 3 ZIPs gained residents, 6 lost.

The county's wealthiest ZIP 51010 (Castana, $89,063 median) and poorest ZIP 51060 (Ute, $52,500) are 8.9 miles apart — a 1.7× income gap across local geography.

Median home values vary 1.6× across this county — from $99,400 in 51060 (Ute) to $159,500 in 51063 (Whiting).

Density varies across the county — from 5 people/sq mi in 51010 (Castana) to 24 in 51040 (Onawa).

Educational attainment ranges from 5.9% bachelor's+ in 51060 (Ute) to 30.7% in 51063 (Whiting) — the breadth of educational profiles across the area.

Within Iowa, this is the #84 most populous of 99 counties and ranks #59 for median household income .

Weighted by population, the typical household earns about $71,524 across the county — reflecting what a typical resident sees, not a simple ZIP average.

19.8% of adults age 25+ hold a bachelor's degree or higher (1,214 of 6,122 reporting).

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

Stories about Monona 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
646
square miles
Avg density
13.5
people per sq mi
Population
8,715
across 9 ZIPs
Onawa
143.8 sq mi
3,500 residents
Mapleton
107.8 sq mi
1,674 residents
Moorhead
82.1 sq mi
549 residents

All ZIP Codes in Monona County


ZIPCityTypePopulationMedian IncomeArea (sq mi)10-yr Growth
51040OnawaStandard3,500$71,179143.8-2.1%
51034MapletonStandard1,674$66,375107.8-7.8%
51063WhitingStandard1,072$80,75079.8-17.7%
51060UteStandard706$52,50058.319.5%
51558MoorheadStandard549$77,41782.1-9.9%
51010CastanaStandard425$89,06381.459.2%
51523BlencoeStandard379$82,62547.56.8%
51572SoldierStandard371$69,50041.7-11.7%
51051RodneyStandard39$51,5633.4-62.1%

Adjacent & Nearby Counties