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Top 5 Most Populous Counties
3 Counties
| County | 2025 Pop. ↓ | Area (mi²) | Density | Change (2020) |
|---|---|---|---|---|
| New Castle County | 593,861 | 426 | 1,394 | 4.01% |
| Sussex County | 278,293 | 936 | 297 | 16.61% |
| Kent County | 195,257 | 586 | 333 | 7.1% |
There are 3 counties in Delaware.
New Castle County is the largest county in the state, with a population of 593,861. The most recent census shows that its population has increased by 0.04% since the previous census.
A number of other Delaware counties also boast relatively large populations for their state, though not able to match the density of New Castle County:
The smallest county in Delaware is Kent County , with a population of just 195,257. This total represents a increase of 0.1% since the last census count was performed.
Other small counties include:
Sussex County , with its sizeable population of 278,293, has shown the largest population growth, with an increase of 0.2% since the last census.
New Castle County has also had relatively high population growth of 0.04% with 593,861 residents.