THE COOK COUNTY LAND BRIEF
Land in the
Valparaiso-Wheaton Morainal Complex setting.
Cook County has 944.9 square miles of land in Illinois. 3 mapped landscape regions meet across Cook County: Valparaiso-Wheaton Morainal Complex, Chicago Lake Plain, Kettle Moraines.
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.
Regional context: Central Corn Belt Plains ↗ · Regional mapping across the county footprint
Where the landscape changes
Cook County intersects 3 mapped regional units. The largest mapped shares are:
- Valparaiso-Wheaton Morainal Complex49.4%
- Chicago Lake Plain47%
- Kettle Moraines3.6%
Southeastern Wisconsin Till Plains in Cook County
Glacial till plains support a transition between hardwood forest, oak savanna and prairie landscapes. Rolling farmland and woodland reflect this meeting of ecological regions in southeastern Wisconsin.
Read the regional source ↗Finding your parcel within Cook County
The atlas lists 162 cities, towns, townships, and Census communities associated with Cook County, including Chicago, Thornton, Bloom. The list includes overlapping geography types and does not divide the county into exclusive service areas.
Cook County by land and water
The Census records 689.7 square miles of water within Cook County, or 42.2% of its total area. That share is close to Cook County’s 42.2%. This is geographic context; waterfront status and usable land must be checked at the parcel.
For scale, Cook County has 4.1 times the land area of nearby Chicago city (227.7 square miles). These areas describe boundaries, not comparable property prices.
The Census boundary meets DuPage County, Kane County, Lake County, McHenry County, Will County within Illinois. A tract near one of these lines should be matched to the county identifier on its own records.

