County Maps US

Johnson County, Iowa

A county in Iowa, ranked 4 of 99 by population.

CountyFIPS 19103

Within Iowa
Johnson County, highlighted, with the areas around it. Boundaries generalised from the 2025 Census cartographic boundary file; neighbour fills carry no data.

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Population
160,044
+6,973 (+4.6%) since 2020
Land area
613
square miles. A further 1.6% of the total area is water
Population density
261
people per square mile, computed rather than published
County seat
Iowa City
Seat of county government.
Established
1837
188 years ago
Largest city
Iowa City city
Population 76,229.

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 Johnson 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 Johnson 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 655 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 Johnson 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
Population160,0444th of 99440th of 3,144
Land area613 sq mi20th of 991,577th of 3,144
Population density261 per sq mi4th of 99487th of 3,144
Median household income$74,93529th of 99845th of 3,143

Full data for Johnson County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population160,044Vintage 2025 Population Estimates
Population in 2020153,071Vintage 2025 Population Estimates
2020 estimates base?152,864Vintage 2025 Population Estimates
Land area613 sq mi2025 Gazetteer Files
Water area10.1 sq mi2025 Gazetteer Files
Total area623.1 sq mi2025 Gazetteer Files
Population density?261 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$74,935American Community Survey 2020-2024 5-Year Estimates
Median home value$308,600American Community Survey 2020-2024 5-Year Estimates
Median age31.0American Community Survey 2020-2024 5-Year Estimates
Households63,341American Community Survey 2020-2024 5-Year Estimates
Housing units68,217American 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
+826
1,719 births, 893 deaths
Net migration
+335
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 Johnson 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
Washington CountyIowa26 mi22,667
Iowa CountyIowa25 mi16,504
Linn CountyIowa24 mi232,028
Cedar CountyIowa18 mi18,359
Muscatine CountyIowa12 mi41,853
Louisa CountyIowa6.0 mi10,416
Benton CountyIowaa single point26,004

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.