County Maps US

Adams County, Indiana

A county in Indiana, ranked 43 of 92 by population.

CountyFIPS 18001

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

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Population
36,650
+798 (+2.2%) since 2020
Land area
338.9
square miles. A further 0.3% of the total area is water
Population density
108
people per square mile, computed rather than published
County seat
Decatur
Seat of county government.
Established
1836
189 years ago
Largest city
Decatur city
Population 10,090.

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 Adams 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 Adams 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 501 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 Adams 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
Population36,65043rd of 921,280th of 3,144
Land area338.9 sq mi71st of 922,715th of 3,144
Population density108 per sq mi37th of 92858th of 3,144
Median household income$65,28962nd of 921,614th of 3,143

Full data for Adams County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population36,650Vintage 2025 Population Estimates
Population in 202035,852Vintage 2025 Population Estimates
2020 estimates base?35,808Vintage 2025 Population Estimates
Land area338.9 sq mi2025 Gazetteer Files
Water area1.0 sq mi2025 Gazetteer Files
Total area340 sq mi2025 Gazetteer Files
Population density?108 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$65,289American Community Survey 2020-2024 5-Year Estimates
Median home value$178,400American Community Survey 2020-2024 5-Year Estimates
Median age33.2American Community Survey 2020-2024 5-Year Estimates
Households12,401American Community Survey 2020-2024 5-Year Estimates
Housing units13,308American 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
+287
624 births, 337 deaths
Net migration
-178
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 Adams 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
Wells CountyIndiana24 mi28,883
Allen CountyIndiana14 mi402,329
Jay CountyIndiana14 mi20,118
Van Wert CountyOhio13 mi29,013
Mercer CountyOhio11 mi42,737

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.