Ranking of Massachusetts Counties By Percentage of Population with Irish Ancestry in 2021

Updated on April 16, 2025.

Based on the US Census ACS-5Yrs estimates, in 2021, there were 1.35M people in Massachusetts with Irish ancestry (19.24% of Massachusetts population). Among all Massachusetts counties, Plymouth County had the highest percentage of its population with Irish ancestry (29.29%), followed by Barnstable County (25.88%), and Norfolk County (24.96%).

The chart and table below shows the top 10 counties with high percentage of its population having Irish ancestry.

You can see similar information for other states and for other ancestry groups in Massachusetts.

Data Source: US Census Bureau.
Ranking of Massachusetts Counties By Percentage of Population with Irish Ancestry in 2021
Plymouth County
Barnstable County
Norfolk County
Essex County
Middlesex County
Dukes County
Nantucket County
Franklin County
Worcester County
Berkshire County
Ranking of Massachusetts Counties By Percentage of Population with Irish Ancestry in 2021
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Rank County Percentage of Pop. (%)
1 Plymouth County 29.29
2 Barnstable County 25.88
3 Norfolk County 24.96
4 Essex County 19.23
5 Middlesex County 18.92
6 Dukes County 18.72
7 Nantucket County 18.59
8 Franklin County 18.10
9 Worcester County 17.95
10 Berkshire County 17.83
11 Hampshire County 17.76
12 Bristol County 17.62
13 Hampden County 13.87
14 Suffolk County 12.49