Montana Counties by Population (2025)

20K

40K

60K

80K

100K

120K

140K

160K

Top 5 Most Populous Counties

Montana flag Yellowstone County

172,789
Montana flag Gallatin County

129,351
Montana flag Missoula County

123,525
Montana flag Flathead County

117,267
Montana flag Cascade County

84,698

56 Counties

County
2025 Pop. ↓
Area (mi²)
Density
Change (2020)
Yellowstone County172,7892.6K664.58%
Gallatin County129,3512.6K508.16%
Missoula County123,5252.6K484.38%
Flathead County117,2675.1K2311.81%
Cascade County84,6982.7K310.34%
Lewis and Clark County77,4653.5K228.83%
Ravalli County48,8602.4K2010.02%
Silver Bow County37,186718525.61%
Lake County34,3081.5K239.76%
Lincoln County22,6653.6K614.85%
Park County18,2032.8K65.69%
Hill County16,5922.9K61.97%
Sanders County14,2842.8K514.66%
Glacier County13,5273K5-1.59%
Jefferson County13,4821.7K811.04%
Big Horn County12,6015K3-3.66%
Fergus County11,9724.3K34.33%
Custer County11,9553.8K30.75%
Carbon County11,7852K612.18%
Richland County11,0592.1K5-4.12%
Beaverhead County10,1615.5K28.3%
Madison County10,0593.6K316.14%
Deer Lodge County9,931737135.42%
Roosevelt County9,8832.4K4-8.5%
Stillwater County9,1811.8K51.98%
Dawson County8,8162.4K4-1.21%
Broadwater County8,5541.2K724.69%
Rosebud County8,1765K2-1.6%
Valley County7,3384.9K1-2.89%
Powell County7,2432.3K34.34%
Blaine County6,7534.2K2-3.62%
Teton County6,5982.3K35.53%
Pondera County6,1911.6K45.32%
Chouteau County5,7254K1-2.95%
Musselshell County5,5861.9K317.6%
Toole County5,2451.9K35.49%
Mineral County5,2301.2K414.49%
Phillips County4,2915.1K11.85%
Sweet Grass County3,8351.9K24.5%
Granite County3,7911.7K214.46%
Sheridan County3,3841.7K2-4.41%
Fallon County2,8821.6K2-4.85%
Meagher County2,1612.4K112.55%
Judith Basin County2,1211.9K15%
Wheatland County2,0951.4K10.92%
Liberty County1,9741.4K11.02%
Powder River County1,7653.3K14.07%
Daniels County1,6091.4K1-2.72%
McCone County1,6062.6K1-7.06%
Carter County1,4483.3K0.433.13%
Garfield County1,1974.7K0.262.13%
Prairie County1,1201.7K12.66%
Wibaux County8768901-6.31%
Golden Valley County8531.2K13.9%
Treasure County80897816.46%
Petroleum County6201.7K0.3724.25%

Overview of Montana Counties

There are 56 counties in Montana.

Yellowstone County is the largest county in the state, with a population of 172,789. The most recent census shows that its population has increased by 0.05% since the previous census.

A number of other Montana counties also boast relatively large populations for their state, though not able to match the density of Yellowstone County:

Montana Counties with the Fewest Residents

The smallest county in Montana is Petroleum County , with a population of just 620. This total represents a increase of 0.2% since the last census count was performed.

Other small counties include:

Montana Counties with Rapid Growth

Broadwater County , with its current population of 8,554, has shown the largest population growth, with an increase of 0.2% since the last census.

On the other hand, Roosevelt County has had the largest decrease in population, with its 9,883 current residents totalling 0.1% less than the previous census.

Sources

  1. US Census State Population Estimates - Most recent state estimates from the Census Bureau's Population Estimates Program
  2. US Census County Population Estimates - Most recent county estimates from the Census Bureau's Population Estimates Program
  3. American Community Survey (2009 - 2013)
  4. Census QuickFacts
  5. Historical Populations of States and Counties (1790 - 1990)

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