County Maps US

Madison County, Iowa

A county in Iowa, ranked 41 of 99 by population.

CountyFIPS 19121

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

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Population
17,270
+639 (+3.8%) since 2020
Land area
561
square miles. A further 0.2% of the total area is water
Population density
30.8
people per square mile, computed rather than published
County seat
Winterset
Seat of county government.
Established
1846
179 years ago
Largest city
Winterset city
Population 5,520.

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 Madison 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 Madison 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 769 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 Madison 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
Population17,27041st of 991,963rd of 3,144
Land area561 sq mi60th of 991,846th of 3,144
Population density30.8 per sq mi38th of 991,901st of 3,144
Median household income$90,8553rd of 99284th of 3,143

Full data for Madison County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population17,270Vintage 2025 Population Estimates
Population in 202016,631Vintage 2025 Population Estimates
2020 estimates base?16,547Vintage 2025 Population Estimates
Land area561 sq mi2025 Gazetteer Files
Water area1.2 sq mi2025 Gazetteer Files
Total area562.2 sq mi2025 Gazetteer Files
Population density?30.8 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$90,855American Community Survey 2020-2024 5-Year Estimates
Median home value$245,100American Community Survey 2020-2024 5-Year Estimates
Median age40.6American Community Survey 2020-2024 5-Year Estimates
Households6,696American Community Survey 2020-2024 5-Year Estimates
Housing units7,100American 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
+2
157 births, 155 deaths
Net migration
+121
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 Madison 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
Warren CountyIowa24 mi57,331
Adair CountyIowa24 mi7,403
Dallas CountyIowa23 mi118,457
Union CountyIowa12 mi11,829
Clarke CountyIowa12 mi9,574
Guthrie CountyIowaa single point10,782
Polk CountyIowaa single point516,546

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.