STATE ยท DE
Counties in Delaware
Delaware has 3 counties and county equivalents. The most populous is New Castle County with 578,592 people (Census 2023 estimate).
| County | Type | FIPS | Population (2023) |
|---|---|---|---|
| Kent County | county | 10001 | 189,789 |
| New Castle County | county | 10003 | 578,592 |
| Sussex County | county | 10005 | 263,509 |
Sources: U.S. Census Bureau geographic reference files; Census Bureau Population Estimates, Vintage 2023. Last reviewed 2026-10-27. Looking for yours? Find your county.