County Maps US

Hamilton County, Ohio

A county in Ohio, ranked 3 of 88 by population.

CountyFIPS 39061

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

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Population
838,418
+8,006 (+1.0%) since 2020
Land area
405.5
square miles. A further 1.7% of the total area is water
Population density
2,068
people per square mile, computed rather than published
County seat
Cincinnati
Seat of county government.
Established
1790
235 years ago
Largest city
Cincinnati city
Population 314,367.

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 Hamilton 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 Hamilton 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 560 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 Hamilton 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
Population838,4183rd of 8876th of 3,144
Land area405.5 sq mi73rd of 882,497th of 3,144
Population density2,068 per sq mi3rd of 8871st of 3,144
Median household income$72,47033rd of 881,014th of 3,143

Full data for Hamilton County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population838,418Vintage 2025 Population Estimates
Population in 2020830,412Vintage 2025 Population Estimates
2020 estimates base?830,631Vintage 2025 Population Estimates
Land area405.5 sq mi2025 Gazetteer Files
Water area7.2 sq mi2025 Gazetteer Files
Total area412.6 sq mi2025 Gazetteer Files
Population density?2,068 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$72,470American Community Survey 2020-2024 5-Year Estimates
Median home value$241,900American Community Survey 2020-2024 5-Year Estimates
Median age36.9American Community Survey 2020-2024 5-Year Estimates
Households354,739American Community Survey 2020-2024 5-Year Estimates
Housing units381,356American 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
+2,159
10,168 births, 8,009 deaths
Net migration
-1,618
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 8 areas bordering Hamilton 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
Butler CountyOhio25 mi400,128
Clermont CountyOhio22 mi216,977
Campbell CountyKentucky16 mi95,441
Boone CountyKentucky14 mi145,316
Dearborn CountyIndiana14 mi51,609
Kenton CountyKentucky7.1 mi175,779
Warren CountyOhio6.5 mi257,181
Franklin CountyIndianaa single point23,286

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

Side by side

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.