New Castle County, DE vs Chester County, PA
Neighbouring counties across the Delaware and Pennsylvania state line, compared on population, size, income and housing. They share 15 mi of border.
New Castle County
Delaware
Chester County
Pennsylvania
Both outlines are drawn at true relative size. Chester County spans about 66.1 km at its widest.
Side by side
| Measure | New Castle County | Difference | Chester County |
|---|---|---|---|
| Population | 588,026 | +5.5% | 557,116 |
| Change since 2020 | 3.0% | -1.2 pp | 4.2% |
| Land area | 426.3 sq mi | -43.2% | 750.6 sq mi |
| Population density | 1,379 per sq mi | +85.8% | 742 per sq mi |
| Median household income | $91,166 | -28.3% | $127,208 |
| Median home value | $352,200 | -27.5% | $485,600 |
| Median age | 39.3 | -3.7% | 40.8 |
| Households | 224,173 | +9.5% | 204,774 |
| Housing units | 236,079 | +11.1% | 212,491 |
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; US Census Bureau, American Community Survey, American Community Survey 2020-2024 5-Year Estimates, released 29 January 2026; US Census Bureau, County Adjacency File, 2025 County Adjacency File, released 15 September 2025. The difference column is computed here: the first county's figure against the second, expressed as a percentage of the second. The change-since-2020 row is the exception: two growth rates differ in percentage points (pp), not percent. Retrieved 30 August 2026.
What the numbers say
- New Castle County holds about 1.1 times the population of Chester County: 588,026 against 557,116.
- Chester County covers more ground, at 750.6 square miles against 426.3.
- New Castle County is the more crowded of the two, at 1,379 people per square mile against 742.
- Median household income is higher in Chester County, by 36,042 dollars a year.
- Since 2020, New Castle County has grown by 3.0% and Chester County has grown by 4.2%.
- They share 15 mi of common border, which the Census Bureau publishes in its county adjacency file and which almost no other county reference presents.
Full pages
Want a different pair? Compare any two of the 3,144 US counties.
Rebuilt from source data 30 August 2026. How these figures are produced.