How many people live in Middlesex County, MA?
Updated Apr. 6, 2026Refreshed annually
In 2024, there were about 1.67 million people living in Middlesex County, MA. That makes Middlesex County the 20th-most populous county in the US. It is also the largest in Massachusetts, accounting for 23.3% of the state’s population.
1.67M
population of Middlesex County, MA (2024)
23.3%
County share of the Massachusetts population (2024)
About 1.67 million people lived in Middlesex County, MA in 2024.
Population estimates, 2000–2024
What are Middlesex County, MA’s age demographics?
About 283,700 Middlesex County, MA residents are aged 65 and older in 2024. That represents 17% of its population. For comparison, the age group represents 18.7% of Massachusetts' population and 18% in the US overall.
Another 319,900 Middlesex County residents, or 19.2% of the population, were children under 18. For comparison, the age group represents 19% of Massachusetts’s population and 21.6% in the US overall.
A lower share of Middlesex County, MA's population is aged under 18 than the US as a whole.
Population estimates by age group, (2024)
What are Middlesex County, MA’s racial and ethnic demographics?
Non-Hispanic white residents make up 66.7% of the Middlesex County, MA population, higher than the national share of 57.5%. Middlesex County, MA also has a larger share of people identifying as non-Hispanic Asian (15.2%) than the US overall (6.5%).
In contrast, Middlesex County’s Hispanic population accounts for 9.8%, below the 20% nationwide, and the non-Hispanic Black or African American population makes up 5.7% of the county, compared with 12.6% nationally.
Racial and ethnic make up differ based on location. These figures reflect how people identified their race alone (not in combination with other races), and separate out Hispanic or Latino ethnicity, following Census reporting standards.
Middlesex County, MA has a higher share of a non-Hispanic Asian population than Massachusetts as a whole.
Population estimates by race and ethnicity, (2024)
The largest city or town in Middlesex County, MA is Cambridge with about 121,200 residents in 2024.
Cities and towns in Middlesex County, MA ranked by population
Population (2024), includes only portions within county
| City or town | Population | |
|---|---|---|
| 1. | Cambridge | 121,186 |
| 2. | Lowell | 120,418 |
| 3. | Newton | 90,700 |
| 4. | Somerville | 82,149 |
| 5. | Framingham | 73,361 |
| 6. | Malden | 66,693 |
| 7. | Waltham | 65,849 |
| 8. | Medford | 59,898 |
| 9. | Everett | 51,825 |
| 10. | Arlington | 47,112 |
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Methodology
USAFacts standardizes data, in areas such as time and demographics, to make it easier to understand and compare.
The analysis was generated with the help of AI and reviewed by USAFacts for accuracy.
Page sources
USAFacts endeavors to share the most up-to-date information available. We sourced the data on this page directly from government agencies; however, the intervals at which agencies publish updated data vary.
