Demographics of Petroleum County, Montana

Petroleum County, Montana had 548 people on July 1, 2025, by the Census Bureau’s estimate: +46 since July 2020. Age, income, poverty, housing and origin below come from the American Community Survey, averaged over 2020–2024, each with its margin of error.

Petroleum County, in four figures

548
Population: July 1, 2025, Vintage 2025 estimate.; +9.2%
Change since July 2020: +46 people.; 51.6 ±6.5
Median age: ACS 2020–⁠2024.; $60,208 ±$16,682
Median household income: ACS 2020–⁠2024, in 2024 dollars.

Population, year by year

July 1 estimates from the Census Bureau’s Vintage 2025. Each year's change is births less deaths, net moves from abroad and net moves from elsewhere in the country, with the Bureau's small residual. The 2020 row's components run 3 months, from the April census to July 1.

Petroleum County, Montana's population grew 9.2% from July 2020 to July 2025, against +3.1% nationally

The July 1 estimate of Petroleum County, Montana's resident population and the nation's, each year of the Census Bureau's Vintage 2025, as a share of its July 2020 level (= 100).

U.S. Census Bureau — Census Bureau population estimates — counties and Puerto Rico municipios, with components of change

About this chart

The figures

Petroleum County, Montana's population grew 9.2% from July 2020 to July 2025, against +3.1% nationally. The July 1 estimate of Petroleum County, Montana's resident population and the nation's, each year of the Census Bureau's Vintage 2025, as a share of its July 2020 level (= 100).
July 1	Population	Index	United States
2020	502	100.0	100.0
2021	520	103.6	100.2
2022	521	103.8	100.7
2023	548	109.2	101.6
2024	538	107.2	102.5
2025	548	109.2	103.1

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Population of Petroleum County, Montana on July 1 of each year, Vintage 2025
July 1	Population	Change	Births less deaths	From elsewhere in the country
2020	502	+4	+2	+3
2021	520	+18	−1	+22
2022	521	+1	0	+1
2023	548	+27	−1	+27
2024	538	−10	+3	−13
2025	548	+10	+2	+7

Age, 2020–2024

The median age is 51.6 ±6.5: for men 49.8 ±10.9 and for women 51.9 ±4.7. Shares are of everyone the survey counts, in the Bureau’s sex-by-age table (B01001).

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People in Petroleum County by age, ACS 2020–2024
Age	People	Share	Montana	United States
Under 5	0 to 32	0% to 7.0%	5.2% ±<0.1	5.6% ±<0.1
5 to 17	53 ±24	11.9% ±4.7	15.8% ±0.2	16.3% ±<0.1
18 to 24	0 to 57	0% to 12.6%	9.0% ±0.2	9.1% ±<0.1
25 to 44	85 ±34	19.0% ±6.2	25.8% ±0.2	26.9% ±<0.1
45 to 64	146 ±46	32.7% ±7.0	24.1% ±0.2	24.8% ±<0.1
65 and over	126 ±36	28.2% ±4.6	20.1% ±0.2	17.2% ±<0.1

A range (the estimate less and plus its margin) where the Bureau's estimate is too uncertain to state as one number: a coefficient of variation over 30%.

Income and poverty, 2020–2024

Median household income is $60,208 ±$16,682, and income per person $39,919 ±$8,205, in 2024 dollars. The median is $72,509 ±$761 in Montana and $80,734 ±$166 in the United States.

Households by income

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Households in Petroleum County by income, ACS 2020–2024
Household income	Households	Share	Montana	United States
Under $25,000	13 to 67	6.9% to 29.3%	15.0% ±0.4	14.6% ±<0.1
$25,000 to $49,999	58 ±23	26.2% ±8.1	19.4% ±0.5	16.7% ±<0.1
$50,000 to $74,999	48 ±21	21.7% ±8.0	17.3% ±0.4	15.5% ±<0.1
$75,000 to $99,999	1 to 27	0.7% to 12.0%	13.6% ±0.4	12.6% ±<0.1
$100,000 to $149,999	11 to 65	5.8% to 28.6%	17.4% ±0.4	17.5% ±<0.1
$150,000 to $199,999	2 to 20	1.1% to 8.9%	8.2% ±0.3	9.6% ±<0.1
$200,000 or more	1 to 23	0.6% to 10.2%	9.0% ±0.3	13.4% ±0.1

A range (the estimate less and plus its margin) where the Bureau's estimate is too uncertain to state as one number: a coefficient of variation over 30%.

Poverty by age

The poverty rate is the share of people whose family income is below the federal threshold for their family’s size, of everyone for whom the Bureau determines it (B17020).

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Poverty rate in Petroleum County by age, ACS 2020–2024
Age	Below poverty	Rate	Montana	United States
All ages	18 to 54	8.1% ±3.6	11.5% ±0.3	12.5% ±0.1
Under 18	0 to 18	0% to 27.0%	12.7% ±0.6	16.1% ±0.1
18 to 59	3 to 33	1.8% to 14.4%	11.7% ±0.4	11.6% ±0.1
60 and over	1 to 31	1.2% to 18.8%	10.3% ±0.4	11.0% ±<0.1

A range (the estimate less and plus its margin) where the Bureau's estimate is too uncertain to state as one number: a coefficient of variation over 30%.

Housing, 2020–2024

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Housing in Petroleum County, ACS 2020–2024
Measure	Petroleum County	Montana	United States
Housing units	311 ±61	528,419 ±3,257	143,775,355 ±10,234
Occupied	71.1% ±10.4	86.8% ±0.5	89.9% ±0.1
Vacant	28.9% ±9.7	13.2% ±0.3	10.1% ±0.1
Owner occupied	72.9% ±14.7	69.2% ±0.6	65.2% ±0.3
Renter occupied	27.1% ±9.2	30.8% ±0.4	34.8% ±0.1
Median home value	$201,400 ±$49,436	$375,800 ±$3,433	$332,700 ±$236
Median gross rent	$800 ±$227	$1,081 ±$14	$1,413 ±$2
Median year built	1983 ±7	1981 ±1	1980 ±1

Occupied and vacant are shares of all housing units; owner and renter occupied are shares of occupied units. Value and rent are medians in 2024 dollars.

Origin and place of birth, 2020–2024

Hispanic or Latino origin is not a race in the Census Bureau’s tables. Here the people of Hispanic origin, of any race, are one row, and everyone else is counted by race alone (B03002), so the rows add to the whole.

Hispanic origin and race

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People in Petroleum County by Hispanic origin and race, ACS 2020–2024
Origin	People	Share	Montana	United States
Hispanic or Latino	0 to 11	0% to 2.5%	4.6% ±<0.1	19.3% ±<0.1
White alone, not Hispanic	442 ±103	98.9% ±32.7	83.6% ±0.2	57.4% ±<0.1
Black alone, not Hispanic	0 to 11	0% to 2.5%	0.4% ±<0.1	11.9% ±<0.1
Asian alone, not Hispanic	0 to 9	0% to 2.0%	0.8% ±0.1	5.9% ±<0.1
American Indian and Alaska Native alone, not Hispanic	0 to 7	0% to 1.6%	5.3% ±0.1	0.5% ±<0.1
Native Hawaiian and Other Pacific Islander alone, not Hispanic	0 to 11	0% to 2.5%	< 0.1% ±<0.1	0.2% ±<0.1
Some other race alone, not Hispanic	0 to 11	0% to 2.5%	0.5% ±0.1	0.6% ±<0.1
Two or more races, not Hispanic	0 to 11	0% to 2.5%	4.7% ±0.2	4.3% ±<0.1

A range (the estimate less and plus its margin) where the Bureau's estimate is too uncertain to state as one number: a coefficient of variation over 30%.

Place of birth and citizenship

“Born a citizen outside the states” counts people born in Puerto Rico, the island areas, or abroad to American parents. Naturalized citizens and those who are not citizens together make up the people born abroad (B05002).

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People in Petroleum County by place of birth and citizenship, ACS 2020–2024
Born	People	Share	Montana	United States
Born in the state	260 ±69	58.2% ±7.2	52.1% ±0.5	57.3% ±<0.1
Born in another state	181 ±64	40.5% ±10.7	44.8% ±0.4	26.9% ±<0.1
Born a citizen outside the states	0 to 5	0% to 1.1%	0.8% ±0.1	1.7% ±<0.1
Born abroad	0 to 12	0% to 2.7%	2.3% ±0.1	14.1% ±<0.1
Naturalized citizens	0 to 12	0% to 2.7%	1.2% ±0.1	7.4% ±<0.1
Not citizens	0 to 11	0% to 2.5%	1.1% ±0.1	6.8% ±<0.1

A range (the estimate less and plus its margin) where the Bureau's estimate is too uncertain to state as one number: a coefficient of variation over 30%.

Petroleum County among the counties of Montana

56th of 56 by population, July 2025. Every one is listed on the Montana page.

Counties of Montana near Petroleum County in population, July 2025
County	July 2025	Change since 2020
Garfield County	1,148	−1.9%
Prairie County	1,112	+1.6%
Wibaux County	885	−5.4%
Golden Valley County	844	+2.7%
Treasure County	728	−4.0%
Petroleum County	548	+9.2%

Elsewhere on the site

Sources

Census Bureau population estimates — counties and Puerto Rico municipios, with components of change — U.S. Census Bureau · U.S. Government work · retrieved September 25, 2026
American Community Survey 5-year estimates — table-based Summary File · U.S. Government work

Data retrieved September 25, 2026