County Maps US

Allen County, Ohio

A county in Ohio, ranked 26 of 88 by population.

CountyFIPS 39003

Within Ohio
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 Lima, the county seat, located via the 2025 Census Gazetteer.

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Population
100,881
-1,235 (-1.2%) since 2020
Land area
402.5
square miles. A further 1.1% of the total area is water
Population density
251
people per square mile, computed rather than published
County seat
Lima
Seat of county government.
Established
1831
194 years ago
Largest city
Lima city
Population 34,695.

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, Ohio 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 591 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 88 counties of Ohio, and among all 3,144 US counties and county-equivalents. Computed from the figures on this page.

MeasureValueIn OhioNationally
Population100,88126th of 88620th of 3,144
Land area402.5 sq mi76th of 882,511th of 3,144
Population density251 per sq mi25th of 88499th of 3,144
Median household income$64,03854th of 881,702nd 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
Population100,881Vintage 2025 Population Estimates
Population in 2020102,116Vintage 2025 Population Estimates
2020 estimates base?102,204Vintage 2025 Population Estimates
Land area402.5 sq mi2025 Gazetteer Files
Water area4.3 sq mi2025 Gazetteer Files
Total area406.9 sq mi2025 Gazetteer Files
Population density?251 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$64,038American Community Survey 2020-2024 5-Year Estimates
Median home value$165,300American Community Survey 2020-2024 5-Year Estimates
Median age39.7American Community Survey 2020-2024 5-Year Estimates
Households41,295American Community Survey 2020-2024 5-Year Estimates
Housing units44,791American 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
+41
1,223 births, 1,182 deaths
Net migration
-117
More people moved out than moved in.

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

The 5 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
Auglaize CountyOhio30 mi45,909
Putnam CountyOhio28 mi34,380
Van Wert CountyOhio15 mi29,013
Hardin CountyOhio12 mi30,072
Hancock CountyOhio6.9 mi75,034

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

All 88 counties of Ohio

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

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