New Castle County: Demographics & People
About 577,961 people live in New Castle County, in 224,173 households. Median age 39.3 years. (2.3y older than Delaware). Population is 26% Black and 12% Hispanic or Latino. County is gaining 1,395 residents per year (2022-2023). County health: 35% adult obesity, 14% smoke.
- 2.6 people per household (vs Delaware avg 2.5).
- 62 dependents per 100 working-age (youth + seniors / 18-64) (vs Delaware 70).
Population & Trend
Current population 577,961; figures track the most recent Census ACS 5-year estimates.
| Population | 577,961 people (vs Delaware 13,439) |
|---|---|
| Total Town Population | 268,756 people |
Sources: Census ACS 5-Year 2024 — county-level query · Refreshed 2026-04-29
Age Distribution
Median age 39.3y is 0.4 years older than the U.S. median (38.9y).
| Age Summary · Total Pop | 577,961 |
|---|---|
| Age Summary · Under 18 | 122,695 |
| Age Summary · 18 To 34 | 132,423.0× |
| Age Summary · 35 To 64 | 224,285.0× |
| Age Summary · 65 Plus | 98,558 |
| Age Summary · Pct Under 18 | 21.2% |
| Age Summary · Pct 18 To 34 | 22.9% |
| Age Summary · Pct 35 To 64 | 38.8% |
| Median age | 39.3 years (vs Delaware 37.0y) |
Sources: Census ACS 5-Year 2024 — county-level query · Refreshed 2026-04-29
Race, Ethnicity & Diversity
Of 577,961 residents, race / ethnicity breaks down by Census ACS counts (a person can identify with one or more groups).
| Census Demographics · Total Population | 577,961 people |
|---|---|
| White residents | 313,334 |
| Black residents | 147,685 |
| Asian residents | 35,810 |
| Census Demographics · Aian | 1,320 |
| Census Demographics · Nhpi | 212 |
| Census Demographics · Other Race | 30,351 |
| Census Demographics · Two Or More Races | 49,249 |
| Diversity Index | 62.7% |
| Asian population | 6.2% (vs Delaware 2.9%) |
| Black population | 25.6% (vs Delaware 26.7%) |
| Hispanic or Latino population | 11.8% (vs Delaware 10.7%) |
Sources: Census ACS 5-Year 2024 — county-level query · Refreshed 2026-04-29
Citizenship & Origin
Where residents were born and their citizenship status (Census ACS). 8.8% are foreign-born — below the U.S. average of 13.9%.
| Census Citizenship · Total | 577,961 |
|---|---|
| Census Citizenship · Native | 503,954 |
| Residents born in this state | 255,871 |
| Residents born in another state | 237,305 |
| Census Citizenship · Foreign Born | 50,548 |
| Census Citizenship · Naturalized | 9,651 |
| Census Citizenship · Non Citizen | 10,778 |
| Foreign-born residents | 8.8% |
Sources: Census ACS 5-Year 2024 — county-level query · Refreshed 2026-04-29
Households & Family Composition
224,173 households.
| Family households | 142,366 households (vs Delaware 3,428) |
|---|---|
| Total households | 224,173 households (vs Delaware 5,560) |
Sources: Census ACS 5-Year 2024 — county-level query · Refreshed 2026-04-29
Residential Stability & Migration
How long residents have lived here and where they came from. The surrounding county is gaining 1,395 residents per year on net (IRS migration data).
| Migration · People moving in (annual) | 500,294 |
|---|---|
| Migration · People moving out (annual) | 498,899 |
| Migration · Net migration (in − out) | 1,395 |
| Migration · Population growing | Yes |
| Migration · Year | 2022-2023 |
Sources: IRS SOI Migration 2022-2023
Disability
Census ACS measures self-reported functional limitations — vision, hearing, mobility, cognitive, self-care, or independent-living. The U.S. baseline disability rate is about 12–13%; rates trend higher with median age.
| Census Disability · Total Pop | 570,679 |
|---|---|
| With Disability | 73,779 |
| Pct With Disability | 12.9% |
Sources: Census ACS 5-Year 2024 — county-level query · Refreshed 2026-04-29
Group Quarters
Group quarters are non-household living arrangements counted by the Census — college dormitories, nursing homes, military barracks, group homes, correctional facilities, and similar institutional or shared housing. 0 residents live in group quarters.
| Census Group Quarters · Total | 16,196 |
|---|
Sources: Census ACS 5-Year 2024 — county-level query · Refreshed 2026-04-29
Other
| Census Mobility · Total | 572,631 |
|---|---|
| Census Mobility · Same House | 509,261 |
| Census Mobility · Same County | 33,774 |
| Census Mobility · Diff County Same State | 4,434 |
| Census Mobility · Diff State | 21,837 |
| Census Mobility · From Abroad | 3,325 |
| Census Mobility · Moved Total | 63,370 |
| Census Mobility · Pct Moved In Year | 11.1% |
| Pct White | 54.2% |
Sources: Census ACS 5-Year 2024 — county-level query · Refreshed 2026-04-29