Delaware County vs Montgomery County
Two neighbouring counties in Pennsylvania, compared on population, size, income and housing. They share 8.2 mi of border.
Delaware County
Pennsylvania
Montgomery County
Pennsylvania
Both outlines are drawn at true relative size. Montgomery County spans about 58.7 km at its widest.
Side by side
| Measure | Delaware County | Difference | Montgomery County |
|---|---|---|---|
| Population | 580,937 | -33.8% | 877,643 |
| Change since 2020 | 0.8% | -1.6 pp | 2.4% |
| Land area | 183.8 sq mi | -61.9% | 482.9 sq mi |
| Population density | 3,161 per sq mi | +74.0% | 1,817 per sq mi |
| Median household income | $89,546 | -21.4% | $113,915 |
| Median home value | $332,200 | -23.9% | $436,700 |
| Median age | 39.1 | -5.1% | 41.2 |
| Households | 216,946 | -35.3% | 335,505 |
| Housing units | 229,715 | -34.4% | 350,351 |
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
- Montgomery County holds about 1.5 times the population of Delaware County: 877,643 against 580,937.
- Montgomery County covers more ground, at 482.9 square miles against 183.8.
- Delaware County is the more crowded of the two, at 3,161 people per square mile against 1,817.
- Median household income is higher in Montgomery County, by 24,369 dollars a year.
- Since 2020, Delaware County has grown by 0.8% and Montgomery County has grown by 2.4%.
- They share 8.2 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.