THE PUTNAM COUNTY LAND BRIEF
Land in the
River Hills setting.
Putnam County has 160.1 square miles of land in Illinois. 3 mapped landscape regions meet across Putnam County: River Hills, Illinois/Indiana Prairies, Upper Mississippi Alluvial Plain.
Broad terraced river valleys contrast with wooded slopes and dissected glacial plains. Bottomland settings and upland oak landscapes occur close together across the Interior River Valleys and Hills.
Regional context: Interior River Valleys and Hills ↗ · Regional mapping across the county footprint
Where the landscape changes
Putnam County intersects 3 mapped regional units. The largest mapped shares are:
- River Hills40.2%
- Illinois/Indiana Prairies38.1%
- Upper Mississippi Alluvial Plain21.7%
Central Corn Belt Plains in Putnam County
Glaciated plains historically supported tallgrass prairie mixed with oak and hickory woodland. Dark prairie soils and broad farming landscapes distinguish much of the Central Corn Belt.
Read the regional source ↗Finding your parcel within Putnam County
The atlas lists 10 cities, towns, townships, and Census communities associated with Putnam County, including Granville, Magnolia, Hennepin. The list includes overlapping geography types and does not divide the county into exclusive service areas.
Putnam County by land and water
The Census records 12 square miles of water within Putnam County, or 7% of its total area. That share is close to Putnam County’s 7%. This is geographic context; waterfront status and usable land must be checked at the parcel.
For scale, Putnam County has 3.9 times the land area of nearby Hennepin township (41.4 square miles). These areas describe boundaries, not comparable property prices.
The Census boundary meets Bureau County, LaSalle County, Marshall County within Illinois. A tract near one of these lines should be matched to the county identifier on its own records.

