Counties · Delaware
Counties of Delaware
Delaware has 3 counties. New Castle County is the largest with 588,026 residents in 2025. 3 of the 3 gained residents between 2020 and 2025 by the Census Bureau's estimates.
What counties are in Delaware?
Sorted by the 2025 population estimate; sort by any column.
| New Castle County | 588,026 | +3.0% | $91,166 |
|---|---|---|---|
| Sussex County | 277,140 | +16.8% | $81,497 |
| Kent County | 194,786 | +7.1% | $74,477 |
Source: PEP Vintage 2025 (CO-EST2025); American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) · Census population estimates
How these figures are made: methodology and release checks · reading a margin of error · every state · corrections