County Maps US

Johnson County, Kansas

The most populous of Kansas's 105 counties.

CountyFIPS 20091

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

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Population
636,906
+25,777 (+4.2%) since 2020
Land area
473.6
square miles. A further 1.3% of the total area is water
Population density
1,345
people per square mile, computed rather than published
County seat
Olathe
Seat of county government.
Established
1855
170 years ago
Largest city
Overland Park city
Population 203,677.

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, Kansas 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 747 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 105 counties of Kansas, and among all 3,144 US counties and county-equivalents. Computed from the figures on this page.

MeasureValueIn KansasNationally
Population636,9061st of 105113th of 3,144
Land area473.6 sq mi99th of 1052,178th of 3,144
Population density1,345 per sq mi1st of 105121st of 3,144
Median household income$109,2081st of 105106th 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
Population636,906Vintage 2025 Population Estimates
Population in 2020611,129Vintage 2025 Population Estimates
2020 estimates base?609,865Vintage 2025 Population Estimates
Land area473.6 sq mi2025 Gazetteer Files
Water area6.3 sq mi2025 Gazetteer Files
Total area479.9 sq mi2025 Gazetteer Files
Population density?1,345 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$109,208American Community Survey 2020-2024 5-Year Estimates
Median home value$391,200American Community Survey 2020-2024 5-Year Estimates
Median age38.6American Community Survey 2020-2024 5-Year Estimates
Households249,531American Community Survey 2020-2024 5-Year Estimates
Housing units259,655American 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
+2,179
6,887 births, 4,708 deaths
Net migration
+3,832
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
Miami CountyKansas24 mi36,240
Wyandotte CountyKansas20 mi170,597
Douglas CountyKansas17 mi120,920
Jackson CountyMissouri14 mi732,994
Leavenworth CountyKansas12 mi84,590
Cass CountyMissouri7.5 mi115,859
Franklin CountyKansasa single point26,299

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

Side by side

All 105 counties of Kansas

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

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