County · code 17147
Piatt CountyIllinois
Piatt County is a county in Illinois, with its seat in Monticello, that was created in 1841.
- Founded1841
- County seatMonticello
- Named forJames Andrew Piatt
- Land area439 sq mi + 0.3 sq mi water
- Population16,673 2020 Census
- Parcels mapped4,501 checked 15 October 2026
Where it is
Piatt on the map of Illinois
Illinois has 102 counties and county equivalents, each with its own records office. Shapes with a page are links.
History
Formed in 1841 from De Witt County and Macon County
An old deed may name a county that no longer exists, or a boundary that has since moved.
Piatt County was formed on January 27, 1841, from De Witt and Macon counties. The county was named after James Andrew Piatt.
- 1841Piatt County created Piatt created from De Witt and Macon. · Ill. Laws 1840-1841, pp. 71-74
Land and parcels
What the maps cover in Piatt
Who publishes each layer, how good it is, and when we last checked.
-
Parcels Good enough
Lot lines and tax-map numbers for 4,501 parcels from Piatt County. Drawn for tax purposes: usually within a few feet of a survey, but not a survey.
edited 26 February 2025 · checked 15 October 2026 -
Address points Missing
No public address points layer found for Piatt County yet.
-
Buildings Reference
Roof outlines traced from aerial imagery from FEMA Response Geospatial Office with Oak Ridge National Laboratory (ORNL). Good for seeing what is on a lot; not accurate enough to set a fence from.
checked 18 October 2026
- Official
- from the office that keeps the record
- Good enough
- a reliable statewide or national copy
- Fallback
- a guide only; check the official record
- Missing
- nothing public found yet
People and land
Piatt by the Census
Source: US Census Bureau, 2020 Census; US Census Bureau, 2020 Gazetteer Files. Not endorsed or certified by the Census Bureau.
Rules and offices
Piatt County's official site
We have found the county's site but not its offices yet; start there.
County government
- County government
The official website of Piatt County.
See your own lot on these maps
Open Piatt County on Parcel Chart's free map and click your parcel. Save it with a free account; the full record of your place (site map, projects, documents) is Pro, in early access.
Questions
Common questions about Piatt County
- When was Piatt County founded?
- Piatt County was founded in 1841, formed from De Witt County and Macon County, and named after James Andrew Piatt.
- What is the county seat of Piatt County?
- The county seat of Piatt County is Monticello.
- Is there an online parcel map for Piatt County?
- Yes. Piatt County publishes a parcel map of 4,501 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
- Has Piatt County's boundary or name changed?
- Piatt County was created in 1841 from De Witt County and Macon County. The Atlas of Historical County Boundaries records no boundary change since.
- Is my lot in a flood zone?
- We do not have flood maps for Piatt County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.
Nearby