THE NEW CASTLE COUNTY LAND BRIEF
Land in the
Delmarva Uplands setting.
New Castle County has 426.3 square miles of land in Delaware. 4 mapped landscape regions meet across New Castle County: Delmarva Uplands, Piedmont Uplands, Delaware River Terraces and Uplands, among others.
Low coastal plains contain terraces, estuaries, marshes and barrier islands. Unconsolidated sediments underlie this varied coastal setting, with forest patterns changing near streams and low-lying areas.
Regional context: Middle Atlantic Coastal Plain ↗ · Regional mapping across the county footprint
Where the landscape changes
New Castle County intersects 4 mapped regional units. The largest mapped shares are:
- Delmarva Uplands58.9%
- Piedmont Uplands21.8%
- Delaware River Terraces and Uplands16.6%
- Chesapeake Rolling Coastal Plain2.8%
Northern Piedmont in New Castle County
Rounded low hills, open valleys and irregular plains form a transition between Appalachian highlands and the coastal plain. The underlying geology mixes metamorphic, igneous and sedimentary rocks.
Read the regional source ↗Southeastern Plains in New Castle County
Irregular plains of sand, silt and clay support a mix of pine and hardwood landscapes. The region has more relief than the lower coastal plain, with generally gentle stream gradients.
Read the regional source ↗Finding your parcel within New Castle County
The atlas lists 28 cities, towns, townships, and Census communities associated with New Castle County, including Middletown, Wilmington, Hockessin. The list includes overlapping geography types and does not divide the county into exclusive service areas.
New Castle County by land and water
The Census records 67.7 square miles of water within New Castle County, or 13.7% of its total area. That share is close to New Castle County’s 13.7%. This is geographic context; waterfront status and usable land must be checked at the parcel.
For scale, New Castle County has 309.2 times the land area of nearby St. Georges CDP (1.38 square miles). These areas describe boundaries, not comparable property prices.
The Census boundary meets Kent County within Delaware. A tract near one of these lines should be matched to the county identifier on its own records.

