In 2018, Petroleum County, MT had a population of 432 people with a median age of 52.1 and a median household income of $44,688. Between 2017 and 2018 the population of Petroleum County, MT declined from 453 to 432, a -4.64% decrease and its median household income declined from $46,429 to $44,688, a -3.75% decrease.
The 5 largest ethnic groups in Petroleum County, MT are White (Non-Hispanic) (98.1%), Asian (Non-Hispanic) (1.85%), White (Hispanic) (0%), Black or African American (Non-Hispanic) (0%), and Black or African American (Hispanic) (0%). 0% of the people in Petroleum County, MT speak a non-English language, and 100% are U.S. citizens.
In 2018, the median property value in Petroleum County, MT was $133,300, and the homeownership rate was 67.4%. Most people in Petroleum County, MT worked at home, and the average commute time was 10.6 minutes. The average car ownership in Petroleum County, MT was 2 cars per household.