THE JOHNSON COUNTY LAND BRIEF
Land in the
Southern Shawnee Hills setting.
Johnson County has 343.7 square miles of land in Illinois. 3 mapped landscape regions meet across Johnson County: Southern Shawnee Hills, Northern Shawnee Hills, Wabash-Ohio Bottomlands.
Open hills, irregular plains and tablelands are developed on limestone and other sedimentary rocks. Oak-hickory woodland, local prairie and cedar-glade settings contribute to this diverse inland plateau.
Regional context: Interior Plateau ↗ · Regional mapping across the county footprint
Where the landscape changes
Johnson County intersects 3 mapped regional units. The largest mapped shares are:
- Southern Shawnee Hills55.4%
- Northern Shawnee Hills39.2%
- Wabash-Ohio Bottomlands5.5%
Interior River Valleys and Hills in Johnson County
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.
Read the regional source ↗Finding your parcel within Johnson County
The atlas lists 7 cities, towns, townships, and Census communities associated with Johnson County, including Vienna, Goreville, Buncombe. The list includes overlapping geography types and does not divide the county into exclusive service areas.
Johnson County by land and water
The Census records 4.95 square miles of water within Johnson County, or 1.4% of its total area. That share is close to Johnson County’s 1.4%. This is geographic context; waterfront status and usable land must be checked at the parcel.
For scale, Johnson County has 121.2 times the land area of nearby Vienna city (2.84 square miles). These areas describe boundaries, not comparable property prices.
The Census boundary meets Massac County, Pope County, Pulaski County, Saline County, Union County, Williamson County within Illinois. A tract near one of these lines should be matched to the county identifier on its own records.

