Irish Population in Massachusetts by County : 2025 Ranking & Insights

According to U.S. Census estimates, the Irish population in Massachusetts totals 1.3 million. Every county in the state reports a non-zero population, with Middlesex County leading at 296,239, followed by Norfolk County (176,988) and Essex County (150,216). This demographic analysis ranks all counties in Massachusetts by their Irish population, offering insights into regional distribution patterns and highlighting county-level concentrations across the state.

Top 5 counties with the largest Irish population in Massachusetts

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  • 1
    Middlesex County
    Irish population in Middlesex County is 296,239
    18.25% of Middlesex County population is Irish
  • 2
    Norfolk County
    Irish population in Norfolk County is 176,988
    24.43% of Norfolk County population is Irish
  • 3
    Essex County
    Irish population in Essex County is 150,216
    18.61% of Essex County population is Irish
  • 4
    Worcester County
    Irish population in Worcester County is 149,259
    17.32% of Worcester County population is Irish
  • 5
    Plymouth County
    Irish population in Plymouth County is 148,162
    27.86% of Plymouth County population is Irish

Overview of Irish population in Massachusetts

  • Population Count and Percentage: American Community Survey show Massachusetts contains 1.3 million Irish residents (18.7% of 7.0 million total state population), positioning the state at the 85th percentile nationally among U.S. states for Irish population concentrations.
  • Comparison to State and National Averages: U.S. Census data records indicate Massachusetts's Irish population of 18.7% exceeds the national average of 9.4% by a factor of 2.
  • Share of Total National Population: Official American Community Survey records show Massachusetts hosts 1.3 million Irish residents, representing 4.2% of the nation's total Irish population of 31.2 million, establishing the state as a significant demographic concentration center within national boundaries.
  • Population Density per Square Mile: U.S. Census Bureau's American Community Survey data shows Massachusetts maintains 167.4 Irish Americans per square mile, representing more than eighteen times the national average of 8.8 per square mile, placing the state among jurisdictions with the highest demographic concentrations nationally.
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14 Counties in Massachusetts Ranked by Irish Population

View Methodology
American Community Survey data [1] show Irish populations across every county in Massachusetts, with demographic distributions ranging from the highest population in Middlesex County to the lowest in $rank_n_geo_name. The table below provides broader statistics, including total population figures, density measures, and demographic distributions based on current ACS data for all counties included in this analysis*.
counties in Massachusetts ranked by Irish population count
Rank by Irish Population
County
Irish Population
% of Total County Population
% of Total Massachusetts Irish Population
5 Year Rank Trend
1 Middlesex County 296,239 18.25% 22.68%
2 Norfolk County 176,988 24.43% 13.55%
3 Essex County 150,216 18.61% 11.50%
4 Worcester County 149,259 17.32% 11.43%
5 Plymouth County 148,162 27.86% 11.34%
6 Suffolk County 98,178 12.55% 7.52%
7 Bristol County 97,058 16.78% 7.43%
8 62,262 13.45% 4.77%
9 58,178 25.29% 4.45%
10 27,346 17.46% 2.09%
11 23,865 18.64% 1.83%
12 12,338 17.40% 0.94%
13 3,346 16.12% 0.26%
14 2,691 18.82% 0.21%
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Methodology

This ranking list is based on data from the American Community Survey (ACS) 5-Year Estimates, conducted by the U.S. Census Bureau. The ACS is one of the most reliable sources for understanding population trends across different locations, and it provides estimates for various racial and ethnic groups at city, county, state and all geography levels down to the Census block group.
This list ranks county in Massachusetts by their Irish population, using the most recent ACS data available.

How the Census defines Irish population

The U.S. Census Bureau allows people to self-identify their ancestry, meaning individuals can write upto ancestries when responding to the survey. In this ranking, we include everyone who identifies as having Irish ancestry, whether alone or in combination with another ancestry.
Here are a few important things to know about how ancestry is reported:
  • Some people identify as Irish alone, while others identify as Irish along with another race (such as Irish and German).
  • We’ve used the “Irish alone or in any combination” category unless noted otherwise, which gives a broader picture of the Irish population in each area.

How We Ranked the Data

This ranking is based on the total number of people who identified as Irish alone or in combination in county. To provide additional context, we’ve also included two key percentages:
  1. % of Total County Population – This shows what percentage of the total state population identifies as Irish .
  2. % of Total Massachusetts Irish Population – This tells us how much of the entire U.S. Irish population lives in that state.
To keep things simple, all population numbers have been rounded to the nearest whole number, and percentages are rounded to one decimal place. Because of rounding, some percentages may not add up to exactly 100%.

Things to Keep in Mind

Like all survey-based data, ACS estimates come with some limitations. Here are a few things to be aware of:
  • In places with very small Irish populations, the numbers may not be reported at all due to privacy protections or sampling variability in the survey.
  • Since the ACS is based on a sample, the numbers are estimates, not exact counts. That means they may slightly differ from other sources like the decennial U.S. Census.
  • County that don’t have any reported Irish population are not included in the ranking but are listed separately below for reference.
This ranking is meant to provide a clear, data-driven look at where Irish populations are most concentrated while keeping the numbers easy to understand.

Sources

  1. 2019-2023 5-Year Estimates.
  2. 2023.