County Maps US

Allen County, Kansas

A county in Kansas, ranked 36 of 105 by population.

CountyFIPS 20001

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

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Population
12,302
-231 (-1.8%) since 2020
Land area
500.3
square miles. A further 1.0% of the total area is water
Population density
24.6
people per square mile, computed rather than published
County seat
Iola
Seat of county government.
Established
1855
170 years ago
Largest city
Iola city
Population 5,240.

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 Allen 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 Allen 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 704 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 Allen 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
Population12,30236th of 1052,268th of 3,144
Land area500.3 sq mi97th of 1052,081st of 3,144
Population density24.6 per sq mi31st of 1052,075th of 3,144
Median household income$60,68971st of 1052,022nd of 3,143

Full data for Allen County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population12,302Vintage 2025 Population Estimates
Population in 202012,533Vintage 2025 Population Estimates
2020 estimates base?12,521Vintage 2025 Population Estimates
Land area500.3 sq mi2025 Gazetteer Files
Water area5.0 sq mi2025 Gazetteer Files
Total area505.3 sq mi2025 Gazetteer Files
Population density?24.6 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$60,689American Community Survey 2020-2024 5-Year Estimates
Median home value$107,600American Community Survey 2020-2024 5-Year Estimates
Median age41.2American Community Survey 2020-2024 5-Year Estimates
Households5,011American Community Survey 2020-2024 5-Year Estimates
Housing units6,077American 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
-67
123 births, 190 deaths
Net migration
+8
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 Allen 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
Anderson CountyKansas24 mi8,018
Neosho CountyKansas24 mi15,637
Bourbon CountyKansas22 mi14,319
Woodson CountyKansas21 mi3,118
Coffey CountyKansasa single point8,467
Linn CountyKansasa single point9,950
Wilson CountyKansasa single point8,299

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

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.