Largest Irish population, US counties · 2010
US counties ranked by the number of residents who are Irish ancestry, from the 2023 American Community Survey detailed-origin tables. Each list covers the full eligible universe; download the complete data as CSV. Cook County, Illinois leads at 523,306. 3,130 counties qualify in total. Massachusetts carries 5 of the top 25 entries.
UPDATED 2026-06-06 · DATA: US CENSUS BUREAU ACS 5-YEAR ESTIMATES
Frequently asked
Which county has the highest irish population?
Cook County, Illinois ranks #1 with 523,306 (2010 American Community Survey).
What are the top 5 counties by irish population?
Cook County, Illinois, Los Angeles County, California, Maricopa County, Arizona, Middlesex County, Massachusetts, Suffolk County, New York.
How many counties are in this ranking?
3,130 counties qualify after filtering for population minimums and data availability. The ranking covers 2010 ACS 5-year data.
How is irish population measured?
Number of residents who are Irish ancestry (Ancestry, ACS detailed tables). Source: US Census Bureau, American Community Survey 5-year estimates (2010).