Petroleum County, Montana Demographics 2026

Population Overview

Petroleum County is located in Montana with a total population of 401. It is the 56th most populous county out of 56 in Montana.

Age Demographics

The median age in Petroleum County is 51.5 years. This is 28% higher than the state median of 40.2 years. Only 13.2% of residents are under 18, indicating fewer families with children. 11.2% of residents are 75 or older, suggesting a significant retirement-age population with implications for healthcare services and senior housing.

Economy, Income & Housing

The median household income in Petroleum County is $59,318. This is 15% lower than the state median of $69,922. Compared to the national median of $78,538, household income here is 24% lower. The poverty rate stands at 6.5%. This is 46% lower than the state poverty rate of 12.0%. The unemployment rate is 0.9%. This is 76% lower than the state rate of 3.8%. The median home value is $173,700. Housing costs are 49% lower than the state median of $338,100. With a home-value-to-income ratio of just 2.9x, Petroleum County is one of the most affordable housing markets in the area. 77.0% of occupied housing units are owner-occupied. This homeownership rate is 11% higher than the state average of 69.4%.

Race & Ethnicity

Petroleum County has a predominantly White (non-Hispanic) population, comprising 99.3% of all residents. Asian residents account for 0.8%.

Education

27.1% of residents aged 25 and older hold a bachelor's degree or higher. This is 21% lower than the state rate of 34.5%. Nationally, 35.0% of adults hold at least a bachelor's degree. The high school graduation rate (or equivalent) is 98.8%.