According to the United States Census Bureau, the county has a total area of 5,212 square miles (13,500 km2), of which 5,140 square miles (13,300 km2) is land and 72 square miles (190 km2) (1.4%) is water.[4] It is the second-largest county in Montana by land area and third-largest by total area.
As of the 2010 census, there were 4,253 people, 1,819 households, and 1,159 families residing in the county. The population density was 0.8 inhabitants per square mile (0.31/km2). There were 2,335 housing units at an average density of 0.5 per square mile (0.19/km2). The racial makeup of the county was 87.0% white, 8.3% American Indian, 0.2% Asian, 0.4% from other races, and 4.0% from two or more races. Those of Hispanic or Latino origin made up 1.9% of the population. In terms of ancestry, 26.2% were Norwegian, 24.3% were German, 13.4% were Irish, 10.1% were American, and 9.0% were English.
Of the 1,819 households, 27.6% had children under the age of 18 living with them, 52.9% were married couples living together, 7.4% had a female householder with no husband present, 36.3% were non-families, and 32.2% of all households were made up of individuals. The average household size was 2.27 and the average family size was 2.86. The median age was 46.8 years.
The median income for a household in the county was $36,453 and the median income for a family was $55,362. Males had a median income of $41,826 versus $26,417 for females. The per capita income for the county was $24,227. About 11.4% of families and 13.5% of the population were below the poverty line, including 17.1% of those under age 18 and 4.8% of those age 65 or over.
Politics
From its creation until 1964, voters of Phillips County were fairly balanced; they selected Democratic Party candidates in 58% of national elections. After 1964 the Republican presidential candidate has garnered the county's vote in every election.
United States presidential election results for Phillips County, Montana[10]
