Piatt County, Illinois
County seat: Monticello · Population 16,791 (2025) · 439 sq mi
Piatt County is the 62nd most populous of Illinois's 102 counties, with 16,791 people (2025 estimate). Its county seat is Monticello. It is part of the East Central region, one of the 10 Illinois economic development regions (DCEO). The map shows its 9 cities and towns and the 6 neighboring counties.
Piatt County facts
- County seat
- Monticello
- Population (2025 estimate)
- 16,791 +0.6% since 2020
- Land area
- 439 sq mi 64th largest of 102
- Water area
- 0 sq mi
- Population density
- 38 per sq mi
- Established
- 1841
- Named after
- James Andrew Piatt influential resident and namesake of Piatt County, Illinois (1789 - 1838)
- Largest city
- Monticello 6,080
- Median household income
- $94,811
- Cities and towns
- 9 plus 2 CDPs
- ZIP codes
- 16
- Time zone
- Central
- FIPS code
- 17147
Cities and towns in Piatt County
Piatt County has 9 incorporated cities, towns and villages. Populations count the people living inside Piatt County; cities that cross a county line also list the other counties.
| Name | Type | Population 2025 | Also in |
|---|---|---|---|
| Monticello (county seat) | City | 6,080 | |
| Bement | Village | 1,462 | |
| Cerro Gordo | Village | 1,312 | |
| Mansfield | Village | 921 | |
| Atwood | Village | 579 | Douglas County |
| Hammond | Village | 499 | |
| De Land | Village | 447 | |
| Cisco | Village | 254 | |
| Ivesdale | Village | 0 | Champaign County |
Unincorporated communities (CDPs)
Census-designated places are communities without their own city government; the county provides their services.
| Community | Population | Also in |
|---|---|---|
| LaPlace | 170 | |
| White Heath | 163 |
ZIP codes in Piatt County
16 ZIP codes reach into Piatt County. ZIP codes ignore county lines, so some also cover a neighboring county.
- 61813
- 61818 also Macon County
- 61830 also Macon County
- 61839
- 61842 also De Witt and McLean counties
- 61851 also Champaign County
- 61853 also Champaign County
- 61854 also McLean County
- 61855
- 61856
- 61875 also Champaign County
- 61882 also De Witt and Macon counties
- 61884 also Champaign County
- 61913 also Douglas and Moultrie counties
- 61929 also Moultrie County
- 61936
Population of Piatt County, 2020–2025
Piatt County grew by 107 people (+0.6%) between April 2020 and July 2025: 212 more deaths than births and a net gain of 313 people from migration.
| Year (July 1) | Population |
|---|---|
| 2020 | 16,688 |
| 2021 | 16,770 |
| 2022 | 16,682 |
| 2023 | 16,736 |
| 2024 | 16,642 |
| 2025 | 16,791 |
Neighboring counties
- Champaign County northeast · 209,972 people
- De Witt County northwest · 15,118 people
- Macon County southwest · 99,300 people
- Moultrie County south · 14,371 people
- Douglas County southeast · 19,880 people
- McLean County north · 171,419 people
Printable Piatt 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) (92 KB)
- PNG (2400 px) (73 KB)
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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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