County Maps US

Iowa County, Iowa

A county in Iowa, ranked 44 of 99 by population.

CountyFIPS 19095

Within Iowa
Iowa County, highlighted, with the areas around it. Boundaries generalised from the 2025 Census cartographic boundary file; neighbour fills carry no data. The dot marks Marengo, the county seat, located via the 2025 Census Gazetteer.

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Population
16,504
-161 (-1.0%) since 2020
Land area
586.5
square miles. A further 0.2% of the total area is water
Population density
28.1
people per square mile, computed rather than published
County seat
Marengo
Seat of county government.
Established
1843
182 years ago
Largest city
Williamsburg city
Population 3,408.

Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025; Wikidata (CC0), Wikidata. Retrieved 30 August 2026.

Satellite view

Aerial imagery of Iowa County with its boundary drawn on top. A map shows you the shape; this shows you what is inside it, and which side of the line a place falls on.

Aerial view of Iowa County, Iowa from the USGS National Map, with its boundary outlined
Imagery: USGS National Map, USGS Imagery Only, public domain, requested from USGS by your browser when you reach this point on the page, at 800 by 800 pixels. The boundary is the 2025 Census cartographic boundary file, reprojected to Web Mercator to match the imagery. You can also open the USGS National Map viewer.

Where Iowa County ranks

Position among the 99 counties of Iowa, and among all 3,144 US counties and county-equivalents. Computed from the figures on this page.

MeasureValueIn IowaNationally
Population16,50444th of 992,005th of 3,144
Land area586.5 sq mi26th of 991,674th of 3,144
Population density28.1 per sq mi46th of 991,983rd of 3,144
Median household income$71,22350th of 991,116th of 3,143

Full data for Iowa County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population16,504Vintage 2025 Population Estimates
Population in 202016,665Vintage 2025 Population Estimates
2020 estimates base?16,669Vintage 2025 Population Estimates
Land area586.5 sq mi2025 Gazetteer Files
Water area1.0 sq mi2025 Gazetteer Files
Total area587.5 sq mi2025 Gazetteer Files
Population density?28.1 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$71,223American Community Survey 2020-2024 5-Year Estimates
Median home value$193,900American Community Survey 2020-2024 5-Year Estimates
Median age42.4American Community Survey 2020-2024 5-Year Estimates
Households6,909American Community Survey 2020-2024 5-Year Estimates
Housing units7,369American Community Survey 2020-2024 5-Year Estimates

Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025; US Census Bureau, American Community Survey, American Community Survey 2020-2024 5-Year Estimates, released 29 January 2026. Population density is computed here, not published: it divides the Vintage 2025 population estimate by the 2025 Gazetteer land area, which are two different Census products. Retrieved 30 August 2026.

How the population changed

The Census Bureau publishes the components behind an estimate, not just the total. For the year to July 2025:

Births minus deaths
-3
191 births, 194 deaths
Net migration
+33
More people moved in than moved out.

Source: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026. Retrieved 30 August 2026.

The 7 areas bordering Iowa County

Ordered by the length of the border actually shared, which the Census Bureau publishes in its county adjacency file and which no other county reference presents.

Bordering areaStateShared borderPopulation
Johnson CountyIowa25 mi160,044
Poweshiek CountyIowa24 mi18,368
Benton CountyIowa24 mi26,004
Keokuk CountyIowa18 mi9,797
Washington CountyIowa6.1 mi22,667
Linn CountyIowaa single point232,028
Tama CountyIowaa single point16,796

Source: US Census Bureau, County Adjacency File, 2025 County Adjacency File, released 15 September 2025. Retrieved 30 August 2026.

All 99 counties of Iowa

Open the interactive Iowa county map, or jump straight to any of them.

Data on this page last rebuilt 30 August 2026. How these figures are produced.