Sullys Hill National Game Preserve and much of the Spirit Lake Indian Reservation are located within the county.
As of the census of 2000, there were 6,964 people, 2,328 households, and 1,701 families residing in the county. The population density was 5 people per square mile (2/km²). There were 2,932 housing units at an average density of 2 per square mile (1/km²). The racial makeup of the county was mostly White (50.85%) and Native American (48.05%). In addition, 0.10% are Black/African American, 0.01% are Asian, 0.01% are Pacific Islander, 0.16% are from other races, and 0.82% are from two or more races. 0.79% of the population were Hispanic or Latino of any race. 25.2% were of Norwegian and 14.8% German ancestry according to Census 2000.
There were 2,328 households out of which 38.00% had children under the age of 18 living with them, 48.50% were married couples living together, 16.60% had a female householder with no husband present, and 26.90% were non-families. 24.50% of all households were made up of individuals and 12.50% had someone living alone who was 65 years of age or older. The average household size was 2.97 and the average family size was 3.48.
In the county the population was spread out with 36.10% under the age of 18, 7.80% from 18 to 24, 23.30% from 25 to 44, 19.40% from 45 to 64, and 13.50% who were 65 years of age or older. The median age was 31 years. For every 100 females there were 102.10 males. For every 100 females age 18 and over, there were 102.00 males.
The median income for a household in the county was $26,688, and the median income for a family was $31,558. Males had a median income of $23,056 versus $17,862 for females. The per capita income for the county was $11,509. About 24.40% of families and 29.10% of the population were below the poverty line, including 38.90% of those under age 18 and 16.70% of those age 65 or over.