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.
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Statewide data for Montana
Population, race, income, age, and trends across Montana
Data from the American Community Survey (ACS) 5-Year estimates.
Source: U.S. Census Bureau ACS, 2026.