Petroleum County's 2026 population is estimated at 489, reflecting a -3.55% growth rate over the past year (World Population Review estimate based on U.S. Census Bureau data). Petroleum County is the 56th largest county in Montana. The 2010 population was 489 and has grown 0% since 2010.
Data after 2023 is projected based on recent change
Overall: 51.6 years
Female: 51.9 years
Male: 49.8 years
There are 381 adults, (126 of whom are seniors) in Petroleum County.
Female: 200 (44.7%)
Male: 247 (55.3%)
The racial composition of Petroleum County includes 98.88% White, and smaller percentages for Asian, Native American and multiracial populations.
| Race | Population ↓ | Percentage (of total) |
|---|---|---|
| White | 442 | 98.88% |
| Asian | 3 | 0.67% |
| Native American | 2 | 0.45% |
Petroleum County 's average per capita income is $40,139. Household income levels show a median of $60,208. The poverty rate stands at 8.05%.
| Name | Median ↓ | Mean |
|---|---|---|
| Married Families | $82,500 | - |
| Families | $73,750 | $91,348 |
| Households | $60,208 | $78,436 |
| Non Families | $33,854 | $57,776 |
Average Income
Median Household Income
Poverty Rate
