County Maps US

Yellowstone County, Montana

The most populous of Montana's 56 counties.

CountyFIPS 30111

Within Montana
Yellowstone County, highlighted, with the areas around it. Boundaries generalised from the 2025 Census cartographic boundary file; neighbour fills carry no data. The dot marks Billings, the county seat, located via the 2025 Census Gazetteer.

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Population
172,692
+7,484 (+4.5%) since 2020
Land area
2,633
square miles. A further 0.6% of the total area is water
Population density
65.6
people per square mile, computed rather than published
County seat
Billings
Seat of county government.
Established
1893
132 years ago
Largest city
Billings city
Population 121,239.

Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025; Wikidata (CC0), Wikidata. Retrieved 30 August 2026.

Satellite view

Aerial imagery of Yellowstone County with its boundary drawn on top. A map shows you the shape; this shows you what is inside it, and which side of the line a place falls on.

Aerial view of Yellowstone County, Montana from the USGS National Map, with its boundary outlined
Imagery: USGS National Map, USGS Imagery Only, public domain, requested from USGS by your browser when you reach this point on the page, at 787 by 800 pixels. The boundary is the 2025 Census cartographic boundary file, reprojected to Web Mercator to match the imagery. You can also open the USGS National Map viewer.

Where Yellowstone County ranks

Position among the 56 counties of Montana, and among all 3,144 US counties and county-equivalents. Computed from the figures on this page.

MeasureValueIn MontanaNationally
Population172,6921st of 56409th of 3,144
Land area2,633 sq mi23rd of 56202nd of 3,144
Population density65.6 per sq mi1st of 561,233rd of 3,144
Median household income$76,5707th of 56744th of 3,143

Full data for Yellowstone County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population172,692Vintage 2025 Population Estimates
Population in 2020165,208Vintage 2025 Population Estimates
2020 estimates base?164,726Vintage 2025 Population Estimates
Land area2,633 sq mi2025 Gazetteer Files
Water area15.6 sq mi2025 Gazetteer Files
Total area2,649 sq mi2025 Gazetteer Files
Population density?65.6 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$76,570American Community Survey 2020-2024 5-Year Estimates
Median home value$349,500American Community Survey 2020-2024 5-Year Estimates
Median age39.0American Community Survey 2020-2024 5-Year Estimates
Households69,897American Community Survey 2020-2024 5-Year Estimates
Housing units74,239American Community Survey 2020-2024 5-Year Estimates

Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025; US Census Bureau, American Community Survey, American Community Survey 2020-2024 5-Year Estimates, released 29 January 2026. Population density is computed here, not published: it divides the Vintage 2025 population estimate by the 2025 Gazetteer land area, which are two different Census products. Retrieved 30 August 2026.

How the population changed

The Census Bureau publishes the components behind an estimate, not just the total. For the year to July 2025:

Births minus deaths
+115
1,903 births, 1,788 deaths
Net migration
+1,019
More people moved in than moved out.

Source: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026. Retrieved 30 August 2026.

The 7 areas bordering Yellowstone County

Ordered by the length of the border actually shared, which the Census Bureau publishes in its county adjacency file and which no other county reference presents.

Bordering areaStateShared borderPopulation
Big Horn CountyMontana95 mi12,752
Musselshell CountyMontana73 mi5,582
Treasure CountyMontana48 mi728
Stillwater CountyMontana40 mi9,445
Carbon CountyMontana25 mi11,466
Golden Valley CountyMontana7.0 mi844
Rosebud CountyMontana3.0 mi8,253

Source: US Census Bureau, County Adjacency File, 2025 County Adjacency File, released 15 September 2025. Retrieved 30 August 2026.

All 56 counties of Montana

Open the interactive Montana county map, or jump straight to any of them.

Data on this page last rebuilt 30 August 2026. How these figures are produced.