RANKING · 2020 CENSUS · 56 SHOWN OF 56

Largest Irish population, Montana counties · 2020

Montana counties ranked by the number of residents who are Irish ancestry, from the 2020 American Community Survey detailed-origin tables. Each list covers the full eligible universe; download the complete data as CSV. This list covers the 56 counties in Montana that qualify, ranked against each other statewide. The median across all 56 is 775.

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SAME RANKING BYCities States Metros

RELATEDLargest American population Highest American population share Largest Arab population Highest Arab population share Largest Egyptian population Highest Egyptian population share

YEAR2010 2020 2024

RANKPLACESTATEPOPIRISH POPULATIONVS 2010

01Yellowstone County, MTMT172,69219,493−3%

02Missoula County, MTMT123,51318,173−5%

03Gallatin County, MTMT128,74015,423−3%

04Flathead County, MTMT115,42913,816+5%

05Lewis and Clark County, MTMT75,33111,586−3%

06Cascade County, MTMT85,0299,201−33%

07Silver Bow County, MTMT36,1188,920−19%

08Ravalli County, MTMT48,5826,461+2%

09Park County, MTMT18,2142,884+13%

10Lake County, MTMT33,3922,823−14%

11Lincoln County, MTMT22,3282,642−14%

12Jefferson County, MTMT13,3292,112−1%

13Deer Lodge County, MTMT9,7092,020−17%

14Custer County, MTMT12,0341,666−21%

15Madison County, MTMT10,0261,571+10%

16Richland County, MTMT11,3771,517+23%

17Hill County, MTMT16,1671,516−26%

18Beaverhead County, MTMT10,0431,509+7%

19Fergus County, MTMT11,8251,424−3%

20Powell County, MTMT7,1571,338−1%

21Dawson County, MTMT8,6921,292−7%

22Sanders County, MTMT14,0621,231−33%

23Carbon County, MTMT11,4661,166−28%

24Teton County, MTMT6,4961,080+22%

25Broadwater County, MTMT8,4931,071+31%

26Stillwater County, MTMT9,4451,071−15%

27Rosebud County, MTMT8,253987+64%

28Glacier County, MTMT13,463775−19%

29Valley County, MTMT7,385749−18%

30Mineral County, MTMT5,185723+2%

31Big Horn County, MTMT12,752640+4%

32Toole County, MTMT5,211626−31%

33Chouteau County, MTMT5,865614−18%

34Pondera County, MTMT6,072604−25%

35Fallon County, MTMT2,959592−15%

36Musselshell County, MTMT5,582527−25%

37Sweet Grass County, MTMT3,762497+4%

38Phillips County, MTMT4,203457−19%

39Granite County, MTMT3,658454−26%

40Roosevelt County, MTMT10,242397−36%

41Meagher County, MTMT2,137355+29%

42Judith Basin County, MTMT2,162352+11%

43Sheridan County, MTMT3,436332−18%

44Wheatland County, MTMT2,100304+25%

45Blaine County, MTMT6,860274−36%

46Daniels County, MTMT1,612244+78%

47Powder River County, MTMT1,781240+3%

48McCone County, MTMT1,720188−8%

49Prairie County, MTMT1,112138+8%

50Carter County, MTMT1,383127−20%

51Wibaux County, MTMT885124−13%

52Liberty County, MTMT1,957103−69%

53Golden Valley County, MTMT84478−48%

54Garfield County, MTMT1,14873−65%

55Treasure County, MTMT72855−35%

56Petroleum County, MTMT54848−39%

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UPDATED 2026-09-11 · DATA: US CENSUS BUREAU DECENNIAL CENSUS