Jefferson County, MT Population By Ancestry in 2021 (ACS-5Yrs)
Updated on March 3, 2025.
Based on the US Census ACS-5Yrs estimates, in 2021, among the 12.06K Jefferson County, MT population, 2.69K had German ancestry (22.31%), 2.37K had English ancestry (19.67%), and 2.30K had Irish ancestry (19.04%).
The chart below shows the top 10 ancestry groups by percentage, and the table below shows both the population and percentages for many ancestry groups.
You can see similar information for other Montana counties, and for Montana.
NB: People could belong to one or more ancestry groups.
Data Source: US Census Bureau.
Jefferson County, MT Population By Ancestry in 2021
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| Ancestry | Population | Percent of Pop. (%) |
|---|---|---|
| German | 2690 | 22.31 |
| English | 2372 | 19.67 |
| Irish | 2295 | 19.04 |
| Unclassified | 2253 | 18.69 |
| Other Groups | 1525 | 12.65 |
| Norwegian | 1181 | 9.80 |
| Swedish | 434 | 3.60 |
| American | 430 | 3.57 |
| Italian | 396 | 3.28 |
| Scottish | 363 | 3.01 |
| European | 358 | 2.97 |
| French (except Basque) | 358 | 2.97 |
| Danish | 349 | 2.90 |
| Polish | 333 | 2.76 |
| Scandinavian | 208 | 1.73 |
| Scotch Irish | 197 | 1.63 |
| Czech | 195 | 1.62 |
| Dutch | 173 | 1.44 |
| French Canadian | 152 | 1.26 |
| British | 107 | 0.89 |
| Russian | 97 | 0.81 |
| Eastern European | 78 | 0.65 |
| Welsh | 78 | 0.65 |
| Greek | 75 | 0.62 |
| Swiss | 74 | 0.61 |
| Finnish | 60 | 0.50 |
| Hungarian | 37 | 0.31 |
| Croatian | 32 | 0.27 |
| Basque | 30 | 0.25 |
| Northern European | 30 | 0.25 |
| Austrian | 26 | 0.22 |
| Subsaharan African | 24 | 0.20 |
| Ethiopian | 24 | 0.20 |
| Slovene | 22 | 0.18 |
| Yugoslavian | 22 | 0.18 |
| Lithuanian | 20 | 0.17 |
| Czechoslovakian | 10 | 0.08 |
| Serbian | 10 | 0.08 |
| Ukrainian | 9 | 0.08 |
| Portuguese | 6 | 0.05 |
| Romanian | 6 | 0.05 |
| Slovak | 4 | 0.03 |
| Canadian | 2 | 0.02 |
| Slavic | 1 | 0.01 |