Irish Population in Illinois by County : 2025 Ranking & Insights

According to U.S. Census estimates, the Irish population in Illinois totals 1.3 million. Every county in the state reports a non-zero population, with Cook County leading at 434,690, followed by DuPage County (123,298) and Will County (92,644). This demographic analysis ranks all counties in Illinois 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 Illinois

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  • 1
    Cook County
    Irish population in Cook County is 434,690
    8.38% of Cook County population is Irish
  • 2
    DuPage County
    Irish population in DuPage County is 123,298
    13.30% of DuPage County population is Irish
  • 3
    Will County
    Irish population in Will County is 92,644
    13.26% of Will County population is Irish
  • 4
    Lake County
    Irish population in Lake County is 74,139
    10.41% of Lake County population is Irish
  • 5
    Kane County
    Irish population in Kane County is 55,048
    10.67% of Kane County population is Irish

Overview of Irish population in Illinois

  • Population Count and Percentage: American Community Survey show Illinois contains 1.3 million Irish residents (10.6% of 12.7 million total state population), positioning the state at the 87th percentile nationally among U.S. states for Irish population concentrations.
  • Comparison to State and National Averages: U.S. Census data records indicate Illinois's Irish population of 10.6% exceeds the national average of 9.4% by a factor of 1.1.
  • Share of Total National Population: Official American Community Survey records show Illinois hosts 1.3 million Irish residents, representing 4.3% 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 indicates Illinois's density of 24.3 Irish Americans per square mile exceeds the national average of 8.8 per square mile by two and three-quarters times, establishing the state as a significant concentration center for Irish demographic communities.
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102 Counties in Illinois Ranked by Irish Population

View Methodology
American Community Survey data [1] show Irish populations across every county in Illinois, with demographic distributions ranging from the highest population in Cook 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 Illinois ranked by Irish population count
Rank by Irish Population
County
Irish Population
% of Total County Population
% of Total Illinois Irish Population
5 Year Rank Trend
1 Cook County 434,690 8.38% 32.23%
2 DuPage County 123,298 13.30% 9.14%
3 Will County 92,644 13.26% 6.87%
4 Lake County 74,139 10.41% 5.50%
5 Kane County 55,048 10.67% 4.08%
6 McHenry County 48,990 15.73% 3.63%
7 Madison County 33,865 12.80% 2.51%
8 32,579 11.50% 2.42%
9 25,817 15.11% 1.91%
10 24,182 9.49% 1.79%
11 23,832 12.21% 1.77%
12 21,807 12.13% 1.62%
13 19,296 9.36% 1.43%
14 17,970 16.48% 1.33%
15 16,715 12.80% 1.24%
16 16,240 12.02% 1.20%
17 15,652 10.95% 1.16%
18 15,364 15.29% 1.14%
19 12,016 11.25% 0.89%
20 10,625 10.36% 0.79%
21 9,175 13.71% 0.68%
22 7,940 15.00% 0.59%
23 7,523 13.63% 0.56%
24 7,005 13.59% 0.52%
25 6,796 12.75% 0.50%
26 6,678 13.55% 0.50%
27 6,446 8.81% 0.48%
28 6,417 13.74% 0.48%
29 6,325 9.71% 0.47%
30 5,927 13.30% 0.44%
31 5,807 11.86% 0.43%
32 5,717 10.85% 0.42%
33 5,422 15.21% 0.40%
34 5,148 11.69% 0.38%
35 5,027 14.76% 0.37%
36 4,628 12.07% 0.34%
37 4,528 13.71% 0.34%
38 4,490 12.04% 0.33%
39 4,308 13.21% 0.32%
40 4,265 12.20% 0.32%
41 4,245 19.37% 0.31%
42 4,145 11.04% 0.31%
43 4,038 10.97% 0.30%
44 3,996 17.09% 0.30%
45 3,665 13.05% 0.27%
46 3,528 13.19% 0.26%
47 3,489 12.52% 0.26%
48 3,447 10.23% 0.26%
49 3,432 10.32% 0.25%
50 3,190 10.58% 0.24%
51 3,129 9.07% 0.23%
52 3,118 11.50% 0.23%
53 2,815 13.19% 0.21%
54 2,403 14.39% 0.18%
55 2,324 6.30% 0.17%
56 2,288 13.75% 0.17%
57 2,161 12.40% 0.16%
58 2,083 12.57% 0.15%
59 2,075 13.54% 0.15%
60 2,049 12.32% 0.15%
61 2,007 9.39% 0.15%
62 2,000 12.94% 0.15%
63 1,967 9.45% 0.15%
64 1,904 12.19% 0.14%
65 1,899 9.10% 0.14%
66 1,862 13.34% 0.14%
67 1,857 11.89% 0.14%
68 1,809 9.73% 0.13%
69 1,789 15.27% 0.13%
70 1,788 13.04% 0.13%
71 1,773 13.77% 0.13%
72 1,669 12.20% 0.12%
73 1,636 10.23% 0.12%
74 1,634 12.20% 0.12%
75 1,630 11.27% 0.12%
76 1,605 10.24% 0.12%
77 1,573 11.94% 0.12%
78 1,557 7.91% 0.12%
79 1,493 12.27% 0.11%
80 1,402 8.26% 0.10%
81 1,365 9.33% 0.10%
82 1,325 11.19% 0.10%
83 1,247 9.34% 0.09%
84 1,173 7.75% 0.09%
85 1,129 10.88% 0.08%
86 1,111 8.66% 0.08%
87 1,110 9.91% 0.08%
88 1,016 11.00% 0.08%
89 1,015 12.73% 0.08%
90 796 12.67% 0.06%
91 760 14.28% 0.06%
92 682 9.99% 0.05%
93 664 11.86% 0.05%
94 652 13.42% 0.05%
95 615 10.05% 0.05%
96 614 12.67% 0.05%
97 546 15.07% 0.04%
98 541 14.40% 0.04%
99 539 8.53% 0.04%
100 376 7.46% 0.03%
101 332 7.54% 0.02%
102 325 6.41% 0.02%
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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 Illinois 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 Illinois 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.