County facts · Land area · October 22, 2026
Largest Counties in Delaware by Area and Population
The largest Delaware counties by land area and by 2023 population, plus the smallest, county seats and a link to each official parcel map.
Looking for the largest counties in Delaware? Delaware has 3 counties covering about 1,949 square miles of land, based on the Census Bureau's 2020 Gazetteer. The largest by land area is Sussex County, at about 936 square miles, roughly 2.2 times the size of the smallest, New Castle County (426 sq mi). Measured by people instead, the largest is New Castle County, with about 578,592 residents in the Census Bureau's July 1, 2023 estimate.
Each table below links the county's Platbookmapper page and its official parcel viewer, so you can go straight from the numbers to the property lines.
Delaware counties at a glance
- Counties: 3
- Land area: about 1,949 sq mi, plus about 540 sq mi of water inside county lines
- Residents, 2023 estimates: about 1,031,890, or about 530 people per square mile of land
- Median county land area: about 586 sq mi
- With a verified public parcel viewer in our directory: 3 of 3 (3 of them through a statewide viewer)
Every county in Delaware points to the same statewide viewer in our directory, the Delaware FirstMap State Parcels, so one search box covers the whole state and the parcel pop-ups look the same on both sides of a county line.
All 3 Delaware counties ranked by land area
| # | County | Seat | Land (sq mi) | Water (sq mi) | 2023 pop. | People per sq mi | Parcel viewer |
|---|---|---|---|---|---|---|---|
| 1 | Sussex County | Georgetown | 936 | 260 | 263,509 | 281 | Delaware FirstMap State Parcels |
| 2 | Kent County | Dover | 586 | 212 | 189,789 | 324 | Delaware FirstMap State Parcels |
| 3 | New Castle County | Wilmington | 426 | 68 | 578,592 | 1,357 | Delaware FirstMap State Parcels |
All 3 ranked by population
- New Castle County: about 578,592 residents (56% of the state)
- Sussex County: about 263,509 residents (26% of the state)
- Kent County: about 189,789 residents (18% of the state)
Water inside the lines
The Census Bureau counts water separately from land, including bays and coastal water inside a county boundary. Sussex County has about 260 sq mi of water (22% of its total area); Kent County has about 212 sq mi of water (27% of its total area); New Castle County has about 68 sq mi of water (14% of its total area).
Using these numbers in a land search
- Land area is not parcel count. A large rural county can hold fewer parcels than a small suburban one, so size alone says little about how busy its parcel map is.
- Search, don't scroll. In a big county, type an address, owner name or parcel number into the viewer's search box, where it has one, instead of panning across the map.
- Records follow the county line. Deeds, plats and tax bills are kept by the county where the parcel sits, so a tract that crosses a county line usually has a parcel number on each side.
- Rounded figures. Land and water areas are rounded to whole square miles (one decimal for very small places). People per square mile is the 2023 estimate divided by land area.
Related guides
More: All Delaware counties on Platbookmapper
Sources
- U.S. Census Bureau Gazetteer files, 2020 county land and water area.
- U.S. Census Bureau, Population Estimates Program, county totals, Vintage 2023 (July 1, 2023 estimates)
- Platbookmapper county GIS directory (live data file behind our county pages, pulled October 22, 2026) for each official parcel viewer.
- County seats: Wikidata (county seat property), cross-checked against Census place names.