County Maps US

Marion County, Indiana

The most populous of Indiana's 92 counties.

CountyFIPS 18097

Within Indiana
Marion County, highlighted, with the areas around it. Boundaries generalised from the 2025 Census cartographic boundary file; neighbour fills carry no data.

Download SVGFull Indiana map downloads

Population
992,196
+15,488 (+1.6%) since 2020
Land area
396
square miles. A further 1.7% of the total area is water
Population density
2,506
people per square mile, computed rather than published
County seat
Indianapolis
Seat of county government.
Established
1822
203 years ago
Largest city
Indianapolis city (balance)
Population 901,116.

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 Marion 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 Marion 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 800 by 788 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 Marion 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
Population992,1961st of 9252nd of 3,144
Land area396 sq mi47th of 922,544th of 3,144
Population density2,506 per sq mi1st of 9251st of 3,144
Median household income$66,34655th of 921,486th of 3,143

Full data for Marion County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population992,196Vintage 2025 Population Estimates
Population in 2020976,708Vintage 2025 Population Estimates
2020 estimates base?977,202Vintage 2025 Population Estimates
Land area396 sq mi2025 Gazetteer Files
Water area7.0 sq mi2025 Gazetteer Files
Total area403 sq mi2025 Gazetteer Files
Population density?2,506 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$66,346American Community Survey 2020-2024 5-Year Estimates
Median home value$224,000American Community Survey 2020-2024 5-Year Estimates
Median age34.4American Community Survey 2020-2024 5-Year Estimates
Households400,432American Community Survey 2020-2024 5-Year Estimates
Housing units441,040American 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
+5,861
14,498 births, 8,637 deaths
Net migration
-3,836
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 7 areas bordering Marion 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
Hendricks CountyIndiana20 mi193,510
Hancock CountyIndiana17 mi90,969
Hamilton CountyIndiana16 mi387,036
Johnson CountyIndiana16 mi174,262
Boone CountyIndiana4.6 mi80,689
Morgan CountyIndiana4.1 mi74,967
Shelby CountyIndiana4.1 mi45,882

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.