New Castle County's 2026 population is estimated at 590,038, reflecting a 0.34% growth rate over the past year (World Population Review estimate based on U.S. Census Bureau data). New Castle County is the largest county in Delaware. The 2010 population was 538,792 and has grown 9.51% since 2010.
Overall: 39.3 years
Female: 40.6 years
Male: 38.2 years
There are 455,266 adults, (98,558 of whom are seniors) in New Castle County.
Female: 297,537 (51.5%)
Male: 280,424 (48.5%)
The racial composition of New Castle County includes 54.21% White, 25.55% Black or African American, 6.2% Asian, 5.25% other race, and smaller percentages for Native American, Native Hawaiian or Pacific Islander and multiracial populations.
| Race | Population ↓ | Percentage (of total) |
|---|---|---|
| White | 313,334 | 54.21% |
| Black or African American | 147,685 | 25.55% |
| Two or more races | 49,249 | 8.52% |
| Asian | 35,810 | 6.2% |
| Other race | 30,351 | 5.25% |
| Native American | 1,320 | 0.23% |
| Native Hawaiian or Pacific Islander | 212 | 0.04% |
New Castle County 's average per capita income is $58,563. Household income levels show a median of $91,166. The poverty rate stands at 10.14%.
| Name | Median ↓ | Mean |
|---|---|---|
| Married Families | $136,923 | $165,410 |
| Families | $114,354 | $142,650 |
| Households | $91,166 | $120,512 |
| Non Families | $54,405 | $72,755 |
Average Income
Median Household Income
Poverty Rate