Adams County, Indiana
County seat: Decatur · Population 36,650 (2025) · 339 sq mi
Adams County is the 43rd most populous of Indiana's 92 counties, with 36,650 people (2025 estimate). Its county seat is Decatur. It is part of the Northeast (Region 3) region, one of the 12 Indiana economic growth regions (DWD / WorkOne regions). The map shows its 4 cities and towns and the 5 neighboring counties.
Adams County facts
- County seat
- Decatur
- Population (2025 estimate)
- 36,650 +2.4% since 2020
- Land area
- 339 sq mi 71st largest of 92
- Water area
- 1 sq mi
- Population density
- 108 per sq mi
- Established
- 1836
- Named after
- John Quincy Adams President of the United States from 1825 to 1829
- Largest city
- Decatur 10,090
- Median household income
- $65,289
- Cities and towns
- 4 plus 3 CDPs
- ZIP codes
- 8
- Time zone
- Eastern
- FIPS code
- 18001
Cities and towns in Adams County
Adams County has 4 incorporated cities, towns and villages. Populations count the people living inside Adams County; cities that cross a county line also list the other counties.
| Name | Type | Population 2025 | Also in |
|---|---|---|---|
| Decatur (county seat) | City | 10,090 | |
| Berne | City | 4,286 | |
| Geneva | Town | 1,293 | |
| Monroe | Town | 901 |
Unincorporated communities (CDPs)
Census-designated places are communities without their own city government; the county provides their services.
| Community | Population | Also in |
|---|---|---|
| Linn Grove | 396 | |
| Pleasant Mills | 124 | |
| Preble | 88 |
ZIP codes in Adams County
8 ZIP codes reach into Adams County. ZIP codes ignore county lines, so some also cover a neighboring county.
- 46711
- 46714 also Wells County
- 46733 also Allen County
- 46740 also Wells County
- 46772
- 46773 also Allen County
- 46777 also Wells and Allen counties
- 47326 also Jay County
Population of Adams County, 2020–2025
Adams County grew by 842 people (+2.4%) between April 2020 and July 2025: 1,638 more births than deaths and a net loss of 806 people from migration.
| Year (July 1) | Population |
|---|---|
| 2020 | 35,852 |
| 2021 | 35,991 |
| 2022 | 36,162 |
| 2023 | 36,438 |
| 2024 | 36,542 |
| 2025 | 36,650 |
Neighboring counties
- Wells County west · 28,883 people
- Allen County north · 402,329 people
- Jay County south · 20,118 people
- Van Wert County, Ohio east · 29,013 people
- Mercer County, Ohio southeast · 42,737 people
Printable Adams County map
The PDF is a vector file with real text: it prints sharp on Letter paper and you can search it for a town. The PNG is 2400 pixels wide for slides and documents. Both are free to use with a credit to WhichCounty.
- PDF (Letter) (71 KB)
- PNG (2400 px) (67 KB)
Paste this code to embed the map on your site:
Sources
- Boundaries: U.S. Census Bureau, 2025 Cartographic Boundary Files (1:500,000).
- Population: Census Bureau county and city estimates, Vintage 2025. CDP populations: American Community Survey 2020–2024.
- Places and ZIP codes: Census Bureau 2026 Gazetteer and 2020 ZIP Code Tabulation Area relationship files.
- County seat, founding year and name origin: Wikidata (CC0), checked against state sources.
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