Petroleum County, Montana

Petroleum County is a located in the  of. As of, the population is 493, making it Montana's least populated county. Its is.

Geography
According to the, the county has a total area of 4,336 (1,674 ). 4,284 km² (1,654 sq mi) of it is land and 52 km² (20 sq mi) of it (1.20%) is water.

Adjacent Counties

 * - north
 * - east
 * - southeast
 * - south
 * - west

Demographics
As of the of 2000, there were 493 people, 211 households, and 136 families residing in the county. The was 0/km² (0/sq mi). There were 292 housing units at an average density of 0/km² (0/sq mi). The racial makeup of the county was 99.19%, 0.20% , 0.20% from , and 0.41% from two or more races. 1.22% of the population were or  of any race. 37.0% were of ,14.3%, 13.2% and 10.9%  ancestry according to.

There were 211 households out of which 31.30% had children under the age of 18 living with them, 55.90% were living together, 5.70% had a female householder with no husband present, and 35.10% were non-families. 31.30% of all households were made up of individuals and 17.50% had someone living alone who was 65 years of age or older. The average household size was 2.34 and the average family size was 2.95.

In the county the population was spread out with 26.00% under the age of 18, 6.10% from 18 to 24, 22.70% from 25 to 44, 28.20% from 45 to 64, and 17.00% who were 65 years of age or older. The median age was 41 years. For every 100 females there were 110.70 males. For every 100 females age 18 and over, there were 111.00 males.

The median income for a household in the county was $24,107, and the median income for a family was $32,667. Males had a median income of $20,694 versus $17,188 for females. The for the county was $15,986. About 21.00% of families and 23.20% of the population were below the, including 25.60% of those under age 18 and 17.30% of those age 65 or over.