Middlesex County, MA vs Hillsborough County, NH
Neighbouring counties across the Massachusetts and New Hampshire state line, compared on population, size, income and housing. They share 34 mi of border.
Middlesex County
Massachusetts
Hillsborough County
New Hampshire
Both outlines are drawn at true relative size. Middlesex County spans about 77.1 km at its widest.
Side by side
| Measure | Middlesex County | Difference | Hillsborough County |
|---|---|---|---|
| Population | 1,669,979 | +285.3% | 433,415 |
| Change since 2020 | 2.8% | +0.3 pp | 2.5% |
| Land area | 817.9 sq mi | -6.7% | 876.5 sq mi |
| Population density | 2,042 per sq mi | +313.4% | 494 per sq mi |
| Median household income | $130,847 | +26.4% | $103,545 |
| Median home value | $727,800 | +72.8% | $421,100 |
| Median age | 38.9 | -5.1% | 41.0 |
| Households | 634,215 | +275.9% | 168,740 |
| Housing units | 664,267 | +273.7% | 177,734 |
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
- Middlesex County holds about 3.9 times the population of Hillsborough County: 1,669,979 against 433,415.
- Hillsborough County covers more ground, at 876.5 square miles against 817.9.
- Middlesex County is the more crowded of the two, at 2,042 people per square mile against 494.
- Median household income is higher in Middlesex County, by 27,302 dollars a year.
- Since 2020, Middlesex County has grown by 2.8% and Hillsborough County has grown by 2.5%.
- They share 34 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.