Ranking of Montana Counties By Population Aged 25 years and above with an Educational attainment of High School Graduate or Equivalent in 2021 (ACS-5Yrs)

Updated on September 3, 2025.

Based on the US Census ACS-5Yrs estimates, in 2021, the population of Montana (aged 25 years and above) who had an educational attainment of High School Graduate or Equivalent was 207,496. Among all Montana counties, Yellowstone County had the highest population (aged 25 years and above) with an educational attainment of High School Graduate or Equivalent (31,356), followed by Flathead County (20,566), and Cascade County (18,023).

The chart below shows the top 10 Montana counties, and the table below shows the ranking of all Montana counties.

You can see similar information for other educational attainments.

You can also see similar information for other states and for the United States.

Ranking of Montana Counties By Population (Aged 25yrs+) with an Educational Attainment of High School Graduate or Equivalent in 2021
Yellowstone County
Flathead County
Cascade County
Missoula County
Gallatin County
Lewis and Clark County
Ravalli County
Silver Bow County
Lincoln County
Lake County
Ranking of Montana Counties By Population (Aged 25yrs+) with an Educational Attainment of High School Graduate or Equivalent in 2021
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Rank County Number of People
1 Yellowstone County 31356
2 Flathead County 20566
3 Cascade County 18023
4 Missoula County 16601
5 Gallatin County 13764
6 Lewis and Clark County 11523
7 Ravalli County 9763
8 Silver Bow County 8313
9 Lincoln County 5771
10 Lake County 5412
11 Sanders County 3703
12 Park County 3586
13 Glacier County 3135
14 Hill County 3042
15 Richland County 2928
16 Deer Lodge County 2770
17 Fergus County 2739
18 Custer County 2544
19 Big Horn County 2521
20 Carbon County 2433
21 Jefferson County 2331
22 Powell County 2293
23 Stillwater County 2062
24 Roosevelt County 2021
25 Dawson County 1976
26 Madison County 1890
27 Beaverhead County 1787
28 Valley County 1766
29 Rosebud County 1740
30 Teton County 1436
31 Chouteau County 1427
32 Musselshell County 1274
33 Toole County 1259
34 Broadwater County 1257
35 Pondera County 1200
36 Mineral County 1158
37 Blaine County 1127
38 Phillips County 1059
39 Sheridan County 890
40 Sweet Grass County 842
41 Fallon County 713
42 Granite County 702
43 Wheatland County 611
44 Meagher County 477
45 Daniels County 460
46 McCone County 426
47 Judith Basin County 423
48 Powder River County 418
49 Carter County 320
50 Liberty County 281
51 Wibaux County 280
52 Garfield County 279
53 Prairie County 263
54 Golden Valley County 234
55 Treasure County 184
56 Petroleum County 137