Massachusetts Population By County in 2021 (ACS-5Yrs)

Updated on February 28, 2025.

Based on the US Census ACS-5Yrs estimates, in 2021, the total population of Massachusetts was 6.99M. Among all Massachusetts counties, Middlesex was the most populated county (1.62M), followed by Worcester (856.86K), and then Essex (804.60K).

On the other hand, the least populated counties were: Nantucket (13.80K), Dukes (20.28K), and Franklin (71.08K).

The chart and table below shows the population of each county and the percentage of Massachusetts population in each county.

You can see similar information for other states and by state for the United States.

Massachusetts Population By County in 2021
Massachusetts Population By County in 2021
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County Population % of State Population
Barnstable 227942 3.26
Berkshire 129089 1.85
Bristol 576070 8.24
Dukes 20277 0.29
Essex 804598 11.51
Franklin 71085 1.02
Hampden 466265 6.67
Hampshire 161810 2.31
Middlesex 1623411 23.22
Nantucket 13795 0.20
Norfolk 720403 10.30
Plymouth 527602 7.55
Suffolk 792647 11.34
Worcester 856858 12.26