Petroleum County, Montana Population 2026
Updated April 2026 · US Census ACS 2023 5-Year Estimates · 56th-largest in Montana
The population of Petroleum County, Montana is 401 as of the 2023 American Community Survey, making it the 56th-largest county in Montana. The median household income is $59,318, the median home value is $173,700, and the median age is 51.5.
The population of Petroleum County has grown 7.4% since 2010 (489 → 525), a +0.51% annualized rate.
401
Population
+0.51%
Annual growth
0
People / sq mi
$59,318
Median Income
$173,700
Median Home Value
Petroleum County covers 1,656 sq mi of land at 0.2 people per square mile.
About Petroleum County, MT
Petroleum County stands apart on settlement density — it is among the most sparsely settled of US counties, at roughly 0 people per square mile. With 401 residents, Petroleum County is a county in Montana.
Median household income is $59,318, below the US median of $78,538. Poverty is among the lowest of comparable US counties, at 2.3% — below the national 12.4%. Homes carry a median value of $173,700, with typical rent around $769.
About 27.1% of adults 25 and older have a bachelor’s degree, below the 35.0% national figure. Remote work is on the higher side at 13.4%, close to the national 14.0%, and the average commute runs about 14 minutes each way.
Petroleum County Population History (2010-2024)
The county of Petroleum County had a population of 489 in 2010 and 525 in 2024, a 7.4% growth over 14 years. The peak was 543 in 2023. Average annual growth rate: 0.55%.
525
Population (2024)
489
Population (2010)
543
Peak (2023)
0.55%
Avg Annual Growth
| Year | Population |
|---|---|
| 2010 | 489 |
| 2011 | 491 |
| 2012 | 505 |
| 2013 | 505 |
| 2014 | 489 |
| 2015 | 475 |
| 2016 | 491 |
| 2017 | 512 |
| 2018 | 517 |
| 2019 | 497 |
| 2020 | 502 |
| 2021 | 520 |
| 2022 | 520 |
| 2023 | 543 |
| 2024 | 525 |
Race & Ethnicity
| White | 99.3% |
| Black or African American | 0.0% |
| Asian | 0.0% |
| Hispanic or Latino (any race) | 0.0% |
| Two or More Races | 0.0% |
Age & Sex
51.5
Median Age
43.4%
Female
56.6%
Male
27.9%
Age 65+
Age Distribution
Children (under 15): 12.7% · Seniors (65+): 27.9%
Income & Poverty
| Median household income | $59,318$-10,604 vs state |
| Mean household income | $79,305 |
| Per-capita income | $39,877 |
| Poverty rate | 2.3%-4.8% vs state |
| Unemployment rate | 0.6% |
| Employment-to-population | 63.5% |
Top Industries by Employment
The largest employment sector in Petroleum County is agriculture, accounting for 38.0% of workers.
How residents commute
0.0%
Drive alone
22.1%
Carpool
57.1%
Public transit
13.4%
Work from home
14.2 min
Avg commute
Housing
$173,700$-164,400 vs state
Median home value
$769
Median rent
77.0%
Homeownership rate
295
Total housing units
67.8%
Occupied
32.2%
Vacant
23.0%
Renter-occupied
Social & access
93.8%
With health insurance
85.0%
With broadband internet
42.1%
Foreign-born
17.8%
Veterans (18+)
7.7%
With a disability
100.0%
Speak language other than English at home
Education
98.8%
High School+
27.1%
Bachelor's+
Largest cities in Montana
Other counties in Montana
Part of Montana
Metro areas in Montana
County rankings
Frequently Asked Questions
Petroleum County, Montana has a population of 401 according to the US Census Bureau's 2023 American Community Survey 5-year estimates, making it the 56th-largest county in Montana. Population density is 0 people per square mile.
The population of Petroleum County has grown 7.4% since 2010 (489 → 525), a +0.51% annualized rate.
The median household income in Petroleum County, Montana is $59,318, with mean (average) household income of $79,305 and per-capita income of $39,877. 2.3% of residents live below the federal poverty level.
In Petroleum County, the largest racial and ethnic groups are White (99.3%). Figures are from the US Census Bureau's 2023 ACS 5-year estimates and reflect self-reported responses.
The median age in Petroleum County, Montana is 51.5 years. Residents are 43.4% female and 56.6% male.
The median home value in Petroleum County is $173,700 and median monthly rent is $769. 77.0% of occupied housing units are owner-occupied. The county has 295 total housing units, 32.2% of which are vacant.
The largest employment sector in Petroleum County, Montana is agriculture, forestry, fishing, and mining, employing 38.0% of workers. The unemployment rate is 0.6%.
Billings is among the largest cities associated with Petroleum County, Montana, with a population of 118,321.
Petroleum County, MT Climate
Petroleum County, MT has an average annual temperature of 7.4°C (45°F) and receives about 343 mm of precipitation per year. The warmest month is July and the coldest is January. Figures are 1970–2000 climate normals.
7.4°C
Avg Temp
343
Precip (mm/yr)
Jul
Hottest Month
Jan
Coldest Month
| Month | Avg (°C/°F) | Precip |
|---|---|---|
| January | -7° / 20° | 14 mm |
| February | -3° / 26° | 9 mm |
| March | 2° / 35° | 16 mm |
| April | 7° / 45° | 31 mm |
| May | 12° / 54° | 68 mm |
| June | 18° / 64° | 57 mm |
| July | 21° / 70° | 40 mm |
| August | 21° / 69° | 34 mm |
| September | 15° / 58° | 31 mm |
| October | 8° / 47° | 20 mm |
| November | 0° / 32° | 11 mm |
| December | -5° / 23° | 12 mm |
1970–2000 normals from WorldClim 2.1 (~9 km grid). Precipitation can be less precise near mountains or coastlines, where rainfall varies sharply over short distances.
Best time to visit Petroleum County, MT
The most comfortable months to visit Petroleum County, MT are typically July, August and June, when temperatures are mildest and rainfall is relatively low. The hottest month is July (around 30°C high). The coldest is January (near -13°C low). May is usually the wettest month.
Where to stay near Petroleum County
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Data from the American Community Survey (ACS) 5-Year estimates.
Source: U.S. Census Bureau ACS, 2026.