Montana Counties by Population (2025)

2025 Pop.

20K

40K

60K

80K

100K

120K

140K

160K

Top 5 Most Populous Counties

56 Counties

County
2025 Pop. ↓
Area (mi²)
Density
Change (2020)
Yellowstone County172,4392.6K654.38%
Gallatin County128,0392.6K497.05%
Missoula County123,4202.6K484.28%
Flathead County115,5595.1K2310.18%
Cascade County84,4212.7K310.01%
Lewis and Clark County75,4463.5K225.99%
Ravalli County48,6142.4K209.45%
Silver Bow County36,075718502.46%
Lake County33,5511.5K237.37%
Lincoln County22,5013.6K613.96%
Park County18,2102.8K65.69%
Hill County15,9492.9K6-1.87%
Sanders County14,0642.8K512.86%
Jefferson County13,5221.7K811.37%
Glacier County13,4293K4-2.29%
Big Horn County12,7675K3-2.42%
Custer County11,9153.8K30.44%
Fergus County11,9084.3K33.82%
Carbon County11,5702K610.04%
Richland County10,9622.1K5-4.96%
Beaverhead County10,1235.5K27.96%
Roosevelt County10,0672.4K4-6.8%
Madison County9,9973.6K315.43%
Deer Lodge County9,937737135.45%
Stillwater County9,6631.8K57.34%
Dawson County8,6422.4K4-3.14%
Broadwater County8,5411.2K724.45%
Rosebud County8,2655K2-0.49%
Valley County7,3934.9K2-2.22%
Powell County7,1182.3K32.59%
Blaine County6,9224.2K2-1.16%
Teton County6,4492.3K33.13%
Pondera County6,0481.6K42.91%
Chouteau County5,8834K1-0.57%
Musselshell County5,5271.9K316.38%
Mineral County5,2551.2K415.04%
Toole County5,1781.9K34.25%
Phillips County4,1805.1K1-0.74%
Sweet Grass County3,7651.9K22.59%
Granite County3,6391.7K210.07%
Sheridan County3,4061.7K2-3.68%
Fallon County2,8931.6K2-4.49%
Judith Basin County2,1231.9K14.94%
Meagher County2,0732.4K17.74%
Wheatland County2,0481.4K1-1.16%
Liberty County1,9091.4K1-2.5%
McCone County1,7502.6K11.21%
Powder River County1,7373.3K12.6%
Daniels County1,6241.4K1-1.75%
Carter County1,3983.3K0.42-0.64%
Garfield County1,1464.7K0.25-2.13%
Prairie County1,1091.7K11.74%
Wibaux County9188901-1.92%
Golden Valley County8591.2K14.63%
Treasure County7119781-6.2%
Petroleum County5071.7K0.311%

Overview of Montana Counties

There are 56 counties in Montana.

Yellowstone County is the largest county in the state, with a population of 172,439. The most recent census shows that its population has increased by 0.04% 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 507. This total represents a increase of 0.0% since the last census count was performed.

Other small counties include:

Montana Counties with Rapid Growth

Broadwater County , with its current population of 8,541, 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 10,067 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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