The largest county in Delaware
There are two right answers. By land area it is Sussex County; by population it is New Castle County. Which one you want depends on what you meant by largest.
Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025. Retrieved 30 August 2026.
By land area
| Rank | Name | Land area | Population |
|---|---|---|---|
| 1 | Sussex County | 936.1 sq mi | 277,140 |
| 2 | Kent County | 586.1 sq mi | 194,786 |
| 3 | New Castle County | 426.3 sq mi | 588,026 |
By population
| Rank | Name | Population | Density |
|---|---|---|---|
| 1 | New Castle County | 588,026 | 1,379 per sq mi |
| 2 | Sussex County | 277,140 | 296 per sq mi |
| 3 | Kent County | 194,786 | 332 per sq mi |
And the smallest
More on Delaware
Rebuilt from source data 30 August 2026. How these figures are produced.