County Maps US

Sullivan County, Indiana

A county in Indiana, ranked 69 of 92 by population.

CountyFIPS 18153

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

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Population
20,831
+11 (+0.1%) since 2020
Land area
447.2
square miles. A further 1.5% of the total area is water
Population density
46.6
people per square mile, computed rather than published
County seat
Sullivan
Seat of county government.
Established
1816
209 years ago
Largest city
Sullivan city
Population 4,229.

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 Sullivan 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 Sullivan 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 734 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 Sullivan 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
Population20,83169th of 921,784th of 3,144
Land area447.2 sq mi21st of 922,280th of 3,144
Population density46.6 per sq mi80th of 921,539th of 3,144
Median household income$56,20486th of 922,396th of 3,143

Full data for Sullivan County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population20,831Vintage 2025 Population Estimates
Population in 202020,820Vintage 2025 Population Estimates
2020 estimates base?20,819Vintage 2025 Population Estimates
Land area447.2 sq mi2025 Gazetteer Files
Water area6.9 sq mi2025 Gazetteer Files
Total area454.1 sq mi2025 Gazetteer Files
Population density?46.6 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$56,204American Community Survey 2020-2024 5-Year Estimates
Median home value$131,100American Community Survey 2020-2024 5-Year Estimates
Median age41.7American Community Survey 2020-2024 5-Year Estimates
Households7,832American Community Survey 2020-2024 5-Year Estimates
Housing units8,791American 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
-51
230 births, 281 deaths
Net migration
+190
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 Sullivan 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
Crawford CountyIllinois30 mi18,648
Vigo CountyIndiana20 mi106,512
Greene CountyIndiana18 mi31,165
Knox CountyIndiana16 mi35,652
Clark CountyIllinois12 mi15,114
Clay CountyIndiana6.0 mi26,410

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

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.