County Maps US

Big Horn County, Montana

A county in Montana, ranked 16 of 56 by population.

CountyFIPS 30003

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

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Population
12,752
-327 (-2.5%) since 2020
Land area
4,998
square miles. A further 0.4% of the total area is water
Population density
2.6
people per square mile, computed rather than published
County seat
Hardin
Seat of county government.
Established
1913
112 years ago
Largest city
Hardin city
Population 3,696.

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 Big Horn 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 Big Horn 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 800 by 525 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 Big Horn 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
Population12,75216th of 562,236th of 3,144
Land area4,998 sq mi5th of 5679th of 3,144
Population density2.6 per sq mi32nd of 562,940th of 3,144
Median household income$58,75039th of 562,196th of 3,143

Full data for Big Horn County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population12,752Vintage 2025 Population Estimates
Population in 202013,079Vintage 2025 Population Estimates
2020 estimates base?13,122Vintage 2025 Population Estimates
Land area4,998 sq mi2025 Gazetteer Files
Water area18.3 sq mi2025 Gazetteer Files
Total area5,016 sq mi2025 Gazetteer Files
Population density?2.6 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$58,750American Community Survey 2020-2024 5-Year Estimates
Median home value$143,400American Community Survey 2020-2024 5-Year Estimates
Median age31.9American Community Survey 2020-2024 5-Year Estimates
Households3,827American Community Survey 2020-2024 5-Year Estimates
Housing units4,527American 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
+54
190 births, 136 deaths
Net migration
-150
More people moved out than moved in.

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

The 7 areas bordering Big Horn 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
Yellowstone CountyMontana95 mi172,692
Rosebud CountyMontana87 mi8,253
Sheridan CountyWyoming81 mi33,241
Carbon CountyMontana77 mi11,466
Treasure CountyMontana40 mi728
Big Horn CountyWyoming17 mi12,024
Powder River CountyMontana14 mi1,781

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.