THE UNION COUNTY LAND BRIEF
Land in the
Southern Shawnee Hills setting.
Union County has 413.4 square miles of land in Illinois. 4 mapped landscape regions meet across Union County: Southern Shawnee Hills, Southern Ozarkian River Bluffs, Middle Mississippi Alluvial Plain, among others.
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
Union County intersects 4 mapped regional units. The largest mapped shares are:
- Southern Shawnee Hills54.2%
- Southern Ozarkian River Bluffs19.4%
- Middle Mississippi Alluvial Plain17.7%
- Northern Shawnee Hills8.7%
Interior River Valleys and Hills in Union 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 Union County
The atlas lists 6 cities, towns, townships, and Census communities associated with Union County, including Anna, Jonesboro, Alto Pass. The list includes overlapping geography types and does not divide the county into exclusive service areas.
Union County by land and water
The Census records 8.7 square miles of water within Union County, or 2.1% of its total area. That share is close to Union County’s 2.1%. This is geographic context; waterfront status and usable land must be checked at the parcel.
For scale, Union County has 111.9 times the land area of nearby Anna city (3.69 square miles). These areas describe boundaries, not comparable property prices.
The Census boundary meets Alexander County, Jackson County, Johnson County, Pulaski County, Williamson County within Illinois. A tract near one of these lines should be matched to the county identifier on its own records.

