County Maps US

Hamilton County, Indiana

A county in Indiana, ranked 4 of 92 by population.

CountyFIPS 18057

Within Indiana
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 Noblesville, the county seat, located via the 2025 Census Gazetteer.

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Population
387,036
+38,025 (+10.9%) since 2020
Land area
394.4
square miles. A further 2.0% of the total area is water
Population density
981
people per square mile, computed rather than published
County seat
Noblesville
Seat of county government.
Established
1823
202 years ago
Largest city
Carmel city
Population 105,634.

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, Indiana 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 797 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 Hamilton County ranks

Position among the 92 counties of Indiana, and among all 3,144 US counties and county-equivalents. Computed from the figures on this page.

MeasureValueIn IndianaNationally
Population387,0364th of 92199th of 3,144
Land area394.4 sq mi50th of 922,553rd of 3,144
Population density981 per sq mi3rd of 92164th of 3,144
Median household income$121,5301st of 9252nd 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
Population387,036Vintage 2025 Population Estimates
Population in 2020349,011Vintage 2025 Population Estimates
2020 estimates base?347,490Vintage 2025 Population Estimates
Land area394.4 sq mi2025 Gazetteer Files
Water area8.1 sq mi2025 Gazetteer Files
Total area402.5 sq mi2025 Gazetteer Files
Population density?981 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$121,530American Community Survey 2020-2024 5-Year Estimates
Median home value$405,500American Community Survey 2020-2024 5-Year Estimates
Median age38.4American Community Survey 2020-2024 5-Year Estimates
Households137,252American Community Survey 2020-2024 5-Year Estimates
Housing units144,746American 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
+1,618
3,962 births, 2,344 deaths
Net migration
+5,723
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 6 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
Tipton CountyIndiana20 mi15,319
Madison CountyIndiana19 mi135,088
Boone CountyIndiana18 mi80,689
Marion CountyIndiana16 mi992,196
Hancock CountyIndiana5.0 mi90,969
Clinton CountyIndiana2.4 mi33,322

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

Side by side

All 92 counties of Indiana

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

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