Montana Counties by Population (2026)

2026 Pop.

20K

40K

60K

80K

100K

120K

140K

160K

Top 5 Most Populous Counties

56 Counties

County
2026 Pop. ↓
Area (mi²)
Density
Change (2020)
Yellowstone County173,8362.6K665.22%
Gallatin County129,9822.6K508.69%
Missoula County124,5552.6K485.25%
Flathead County116,4915.1K2311.08%
Cascade County85,3902.7K321.16%
Lewis and Clark County75,5703.5K226.17%
Ravalli County49,1272.4K2110.62%
Silver Bow County36,145718502.66%
Lake County33,4011.5K226.9%
Lincoln County22,5093.6K614.04%
Park County18,2552.8K75.96%
Hill County16,2192.9K6-0.18%
Sanders County14,2322.8K514.28%
Jefferson County13,4271.7K810.59%
Glacier County13,4113K4-2.37%
Big Horn County12,6575K3-3.23%
Custer County12,0913.8K31.95%
Fergus County11,8244.3K33.06%
Richland County11,6832.1K61.35%
Carbon County11,4282K68.72%
Madison County10,2803.6K318.75%
Roosevelt County10,2742.4K4-4.94%
Beaverhead County10,0965.5K27.69%
Deer Lodge County9,652737132.41%
Stillwater County9,4611.8K55.15%
Broadwater County8,6971.2K726.78%
Dawson County8,6452.4K4-3.09%
Rosebud County8,2885K2-0.25%
Valley County7,3854.9K1-2.37%
Powell County7,1932.3K33.63%
Blaine County6,8444.2K2-2.35%
Teton County6,5532.3K34.81%
Pondera County6,0791.6K43.33%
Chouteau County5,8774K1-0.58%
Musselshell County5,7121.9K320.3%
Toole County5,2691.9K36.08%
Mineral County5,1831.2K413.49%
Phillips County4,2105.1K10.05%
Sweet Grass County3,7061.9K20.87%
Granite County3,6771.7K211.19%
Sheridan County3,3941.7K2-4.12%
Fallon County2,9581.6K2-2.34%
Judith Basin County2,2091.9K19.09%
Meagher County2,1792.4K113.37%
Wheatland County2,1421.4K23.23%
Liberty County1,9631.4K10.36%
Powder River County1,8043.3K16.49%
McCone County1,7252.6K1-0.35%
Daniels County1,5811.4K1-4.18%
Carter County1,3443.3K0.40-4.41%
Garfield County1,1214.7K0.24-4.19%
Prairie County1,1161.7K12.01%
Wibaux County8588901-8.33%
Golden Valley County8441.2K12.68%
Treasure County7219781-4.88%
Petroleum County5581.7K0.3411.16%

Overview of Montana Counties

There are 56 counties in Montana.

Yellowstone County is the largest county in the state, with a population of 173,836. 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 558. This total represents a increase of 0.1% since the last census count was performed.

Other small counties include:

Montana Counties with Rapid Growth

Broadwater County , with its current population of 8,697, has shown the largest population growth, with an increase of 0.3% since the last census.

On the other hand, Wibaux County has had the largest decrease in population, with its 858 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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