County Maps US

Petroleum County, Montana

The least populous of Montana's 56 counties.

CountyFIPS 30069Sparse data

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

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Population
548
+46 (+9.2%) since 2020
Land area
1,656
square miles. A further 1.1% of the total area is water
Population density
0.33
people per square mile, computed rather than published
County seat
Winnett
Seat of county government.
Established
1926
99 years ago
Largest city
Winnett town
Population 205.

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 Petroleum 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 Petroleum 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 607 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 Petroleum 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
Population54856th of 563,136th of 3,144
Land area1,656 sq mi43rd of 56366th of 3,144
Population density0.33 per sq mi55th of 563,128th of 3,144
Median household income$60,20835th of 562,060th of 3,143

Full data for Petroleum County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population548Vintage 2025 Population Estimates
Population in 2020502Vintage 2025 Population Estimates
2020 estimates base?498Vintage 2025 Population Estimates
Land area1,656 sq mi2025 Gazetteer Files
Water area18.9 sq mi2025 Gazetteer Files
Total area1,675 sq mi2025 Gazetteer Files
Population density?0.33 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$60,208American Community Survey 2020-2024 5-Year Estimates
Median home value$201,400American Community Survey 2020-2024 5-Year Estimates
Median age51.6American Community Survey 2020-2024 5-Year Estimates
Households221American Community Survey 2020-2024 5-Year Estimates
Housing units311American 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
+2
5 births, 3 deaths
Net migration
+7
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 5 areas bordering Petroleum 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
Garfield CountyMontana102 mi1,148
Fergus CountyMontana84 mi11,825
Musselshell CountyMontana38 mi5,582
Phillips CountyMontana30 mi4,203
Rosebud CountyMontana16 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.