What are the fastest-growing counties in Montana?
Madison County is the fastest-growing county in Montana: its population grew 2.98% a year from 2020 to 2025, to 10,026 residents (Census PEP Vintage 2025). Lincoln County (2.50%) and Sanders County (2.46%) follow. Montana as a whole grew 1.04% a year to 1,144,694 residents.
Data as of 2026-09-23. Population, growth and migration: PEP Vintage 2025 · 2020–2025. Income migration: IRS SOI 2022–2023 (2-yr lag).
Top 10 counties in Montana by population growth, 2020 to 2025
| Rank | County | Population | Growth (% per year) | Net domestic migration | Net international migration | IRS net AGI migration |
|---|---|---|---|---|---|---|
| 1 | Madison County | 10,026 | 2.98% | +1,447 | +68 | +$9.4M |
| 2 | Lincoln County | 22,328 | 2.50% | +3,235 | +20 | +$26.8M |
| 3 | Sanders County | 14,062 | 2.46% | +1,979 | +1 | +$14.7M |
| 4 | Flathead County | 115,429 | 1.94% | +10,147 | +342 | +$122.1M |
| 5 | Jefferson County | 13,329 | 1.88% | +1,444 | +20 | +$14.4M |
| 6 | Ravalli County | 48,582 | 1.81% | +5,064 | +167 | +$61.1M |
| 7 | Carbon County | 11,466 | 1.75% | +981 | +18 | +$9.5M |
| 8 | Gallatin County | 128,740 | 1.48% | +5,435 | +1,354 | +$58.8M |
| 9 | Beaverhead County | 10,043 | 1.39% | +810 | -3 | +$8.4M |
| 10 | Lake County | 33,392 | 1.34% | +2,489 | +52 | +$29.4M |
Where are people moving in Montana?
Flathead County gained the most people from elsewhere in the United States: net domestic migration of +10,147 from 2020 to 2025 (Census PEP Vintage 2025). The table ranks every Montana place with 10,000 or more residents by that figure; the IRS column shows net adjusted gross income migration for 2022 to 2023.
| Rank | County | Population | Growth (% per year) | Net domestic migration | Net international migration | IRS net AGI migration |
|---|---|---|---|---|---|---|
| 1 | Flathead County | 115,429 | 1.94% | +10,147 | +342 | +$122.1M |
| 2 | Yellowstone County | 172,692 | 0.89% | +6,685 | +705 | +$16.9M |
| 3 | Gallatin County | 128,740 | 1.48% | +5,435 | +1,354 | +$58.8M |
| 4 | Ravalli County | 48,582 | 1.81% | +5,064 | +167 | +$61.1M |
| 5 | Lewis and Clark County | 75,331 | 1.14% | +4,286 | +199 | +$20.7M |
| 6 | Missoula County | 123,513 | 0.86% | +4,137 | +718 | +$40.5M |
| 7 | Lincoln County | 22,328 | 2.50% | +3,235 | +20 | +$26.8M |
| 8 | Lake County | 33,392 | 1.34% | +2,489 | +52 | +$29.4M |
| 9 | Sanders County | 14,062 | 2.46% | +1,979 | +1 | +$14.7M |
| 10 | Silver Bow County | 36,118 | 0.51% | +1,603 | +196 | +$10.6M |
Go past the headline numbers
The interactive Demographics map layer and the full report for a single place are part of paid plans.
Get the Demographics Report for Madison CountyFrequently asked questions
- What are the fastest-growing counties in Montana?
- By population growth from 2020 to 2025, the fastest are Madison County (2.98% a year), Lincoln County (2.50% a year), Sanders County (2.46% a year), Flathead County (1.94% a year) and Jefferson County (1.88% a year) (Census PEP Vintage 2025). Only places with 10,000 or more residents are ranked.
- Where are people moving in Montana?
- By net domestic migration from 2020 to 2025, the largest gains are Flathead County (+10,147), Yellowstone County (+6,685) and Gallatin County (+5,435) (Census PEP Vintage 2025).
- How fast is Montana growing overall?
- Montana grew 1.04% a year from 2020 to 2025, to 1,144,694 residents, with net migration of +61,545 people (Census PEP Vintage 2025).
- Where does this Montana data come from, and how current is it?
- Population, growth and migration come from the U.S. Census Bureau Population Estimates Program (PEP Vintage 2025 · 2020–2025). Income migration comes from IRS Statistics of Income (IRS SOI 2022–2023 (2-yr lag)). Counties with fewer than 10,000 residents are not ranked (33 of 56 in Montana). Data last loaded 2026-09-23.
Data as of 2026-09-23: sources and periods
- Population, growth and migration
- U.S. Census Bureau, Population Estimates Program: PEP Vintage 2025 · 2020–2025. census.gov/programs-surveys/popest
- Income migration (net AGI)
- Internal Revenue Service, Statistics of Income migration data: IRS SOI 2022–2023 (2-yr lag). irs.gov/statistics/soi-tax-stats-migration-data
How to read the table
- Population is the Census July 1 estimate of the latest vintage.
- Growth is the compound annual rate over 2020 to 2025.
- Net domestic and international migration are cumulative people over 2020 to 2025.
- IRS net AGI migration is adjusted gross income that moved in, less what moved out, for 2022 to 2023. A plus sign means a net inflow.
- Places with fewer than 10,000 residents are left out of the rankings.