Carroll County, Illinois
County seat: Mount Carroll · Population 15,419 (2025) · 445 sq mi
Carroll County is the 67th most populous of Illinois's 102 counties, with 15,419 people (2025 estimate). Its county seat is Mount Carroll. It is part of the Northwest region, one of the 10 Illinois economic development regions (DCEO). The map shows its 7 cities and towns and the 6 neighboring counties.
Carroll County facts
- County seat
- Mount Carroll
- Population (2025 estimate)
- 15,419 −1.9% since 2020
- Land area
- 445 sq mi 60th largest of 102
- Water area
- 22 sq mi
- Population density
- 35 per sq mi
- Established
- 1839
- Same name
- One of 13 Carroll Counties in the US
- Named after
- Charles Carroll of Carrollton American planter and signatory of the Declaration of Independence (1737-1832)
- Largest city
- Savanna 2,699
- Median household income
- $60,758
- Cities and towns
- 7 plus 1 CDPs
- ZIP codes
- 11
- Time zone
- Central
- FIPS code
- 17015
Cities and towns in Carroll County
Carroll County has 7 incorporated cities, towns and villages. Populations count the people living inside Carroll County; cities that cross a county line also list the other counties.
| Name | Type | Population 2025 | Also in |
|---|---|---|---|
| Savanna | City | 2,699 | |
| Thomson | Village | 1,606 | |
| Lanark | City | 1,452 | |
| Mount Carroll (county seat) | City | 1,432 | |
| Milledgeville | Village | 988 | |
| Shannon | Village | 835 | |
| Chadwick | Village | 476 |
Unincorporated communities (CDPs)
Census-designated places are communities without their own city government; the county provides their services.
| Community | Population | Also in |
|---|---|---|
| Lake Carroll | 853 |
ZIP codes in Carroll County
11 ZIP codes reach into Carroll County. ZIP codes ignore county lines, so some also cover a neighboring county.
- 61014 also Whiteside County
- 61028 also Jo Daviess County
- 61046
- 61051 also Ogle County
- 61053 also Jo Daviess County
- 61062 also Stephenson and Jo Daviess counties
- 61064 also Ogle, Lee and Whiteside counties
- 61074 also Jo Daviess County
- 61078 also Stephenson and Ogle counties
- 61270 also Whiteside County
- 61285
Population of Carroll County, 2020–2025
Carroll County shrank by 301 people (−1.9%) between April 2020 and July 2025: 478 more deaths than births and a net gain of 191 people from migration.
| Year (July 1) | Population |
|---|---|
| 2020 | 15,686 |
| 2021 | 15,723 |
| 2022 | 15,563 |
| 2023 | 15,540 |
| 2024 | 15,468 |
| 2025 | 15,419 |
Neighboring counties
- Whiteside County south · 54,121 people
- Jo Daviess County northwest · 21,594 people
- Ogle County east · 51,399 people
- Jackson County, Iowa west · 19,288 people
- Stephenson County northeast · 43,220 people
- Clinton County, Iowa west · 46,002 people
Printable Carroll 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) (89 KB)
- PNG (2400 px) (63 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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