Montana Counties by Population (2025)

The most populous counties in Montana are Yellowstone County with 171,583, Gallatin County at 126,984, Missoula County with 122,546, Flathead County at 114,527, and Cascade County with 84,523. You can get the most current Census population data for all 56 Montana counties, sorted from the most populous counties in Montana to the least, according to the 2024 Population Estimates Program.

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