Irish Population in Montana by County : 2025 Ranking & Insights

According to U.S. Census estimates, the Irish population in Montana stands at 147,931. Every county reports a non-zero population, with Yellowstone County leading at 21,986, followed by Missoula County (17,753) and Gallatin County (16,347). The combined total across counties is slightly lower than the statewide figure - a gap that may reflect rounding, data lag, or unassigned residents in certain census tracts. This analysis ranks all counties in Montana by their Irish population, offering a localized perspective on how the community is distributed across the state.

Top 5 counties with the largest Irish population in Montana

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  • 1
    Yellowstone County
    Irish population in Yellowstone County is 21,986
    13.14% of Yellowstone County population is Irish
  • 2
    Missoula County
    Irish population in Missoula County is 17,753
    14.84% of Missoula County population is Irish
  • 3
    Gallatin County
    Irish population in Gallatin County is 16,347
    13.38% of Gallatin County population is Irish
  • 4
    Flathead County
    Irish population in Flathead County is 14,525
    13.39% of Flathead County population is Irish
  • 5
    Lewis and Clark County
    Irish population in Lewis and Clark County is 11,945
    16.46% of Lewis and Clark County population is Irish

Overview of Irish population in Montana

  • Population Count and Percentage: American Community Survey show Montana contains 147,931 Irish residents (13.4% of 1.1 million total state population), positioning the state at the 14th percentile nationally among U.S. states for Irish population concentrations.
  • Comparison to State and National Averages: U.S. Census data records indicate Montana's Irish population of 13.4% exceeds the national average of 9.4% by a factor of 1.4.
  • Share of Total National Population: Official American Community Survey data indicates Montana contains 147,931 Irish residents, representing less than 1% of the nation's total Irish population of 31.2 million, constituting a minimal fraction of the national demographic community relative to the state's overall population size.
  • Population Density per Square Mile: U.S. Census Bureau's American Community Survey document Montana with 1 Irish Americans per square mile, below the national average of 8.8 per square mile, placing the state among jurisdictions with below-average demographic concentrations nationally.
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55 Counties in Montana Ranked by Irish Population

View Methodology
American Community Survey data [1] show Irish populations across every county in Montana, with demographic distributions ranging from the highest population in Yellowstone 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 Montana ranked by Irish population count
Rank by Irish Population
County
Irish Population
% of Total County Population
% of Total Montana Irish Population
5 Year Rank Trend
1 Yellowstone County 21,986 13.14% 14.86%
2 Missoula County 17,753 14.84% 12.00%
3 Gallatin County 16,347 13.38% 11.05%
4 Flathead County 14,525 13.39% 9.82%
5 Lewis and Clark County 11,945 16.46% 8.07%
6 Cascade County 10,522 12.44% 7.11%
7 Silver Bow County 8,622 24.23% 5.83%
8 5,899 12.88% 3.99%
9 3,538 11.03% 2.39%
10 2,925 16.73% 1.98%
11 2,427 11.75% 1.64%
12 2,213 17.70% 1.50%
13 1,609 13.48% 1.09%
14 1,553 12.01% 1.05%
15 1,507 16.79% 1.02%
16 1,335 15.04% 0.90%
17 1,311 13.67% 0.89%
18 1,287 11.83% 0.87%
19 1,249 7.68% 0.84%
20 1,242 10.96% 0.84%
21 1,209 13.36% 0.82%
22 1,208 16.53% 0.82%
23 1,185 10.23% 0.80%
24 1,056 15.02% 0.71%
25 883 6.44% 0.60%
26 861 13.69% 0.58%
27 766 9.30% 0.52%
28 673 13.39% 0.45%
29 661 5.10% 0.45%
30 628 8.33% 0.42%
31 622 12.27% 0.42%
32 538 8.95% 0.36%
33 485 10.11% 0.33%
34 469 7.97% 0.32%
35 460 16.33% 0.31%
36 455 13.31% 0.31%
37 390 10.50% 0.26%
38 381 9.02% 0.26%
39 353 17.84% 0.24%
40 344 16.79% 0.23%
41 333 16.22% 0.23%
42 327 3.07% 0.22%
43 295 8.02% 0.20%
44 268 3.83% 0.18%
45 231 15.16% 0.16%
46 192 10.90% 0.13%
47 167 13.35% 0.11%
48 161 17.16% 0.11%
49 157 11.54% 0.11%
50 156 8.58% 0.11%
51 141 7.16% 0.10%
52 140 12.20% 0.09%
53 94 12.35% 0.06%
54 88 10.48% 0.06%
55 47 11.72% 0.03%
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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 Montana 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 Montana 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.