Adjacent counties

• Pend Oreille County, Washington– northwest
• Boundary County – north
• Lincoln County, Montana – east/Mountain Time Border
• Sanders County, Montana – southeast/Mountain Time Border
• Shoshone County – southeast
• Kootenai County – south
• Spokane County, Washington – southwest

National protected areas

• Pacific Northwest National Scenic Trail (part)
• Coeur d'Alene National Forest (part)
• Kaniksu National Forest (part)
• Kootenai National Forest (part)

Major highways

• US 2
• US 95
• SH-41
• SH-57
• SH-200

Rivers and lakes

2000 census

As of the census^[15] of 2000, there were 36,835 people, 14,693 households, and 10,270 families living in the county. The population density was 21 people per square mile (8.1 people/km²). There were 19,646 housing units at an average density of 11 units per square mile (4.2 units/km²). The racial makeup of the county was 96.58% White, 0.11% Black or African American, 0.87% Native American, 0.27% Asian, 0.05% Pacific Islander, 0.42% from other races, and 1.70% from two or more races. 1.64% of the population were Hispanic or Latino of any race. 20.9% were of German, 11.7% English, 11.7% American, 9.6% Irish and 5.3% Norwegian ancestry.

There were 14,693 households, out of which 30.60% had children under the age of 18 living with them, 58.60% were married couples living together, 7.50% had a female householder with no husband present, and 30.10% were non-families. 24.00% of all households were made up of individuals, and 8.20% had someone living alone who was 65 years of age or older. The average household size was 2.49 and the average family size was 2.94.

In the county, the population was spread out, with 25.50% under the age of 18, 6.70% from 18 to 24, 25.40% from 25 to 44, 29.30% from 45 to 64, and 13.10% who were 65 years of age or older. The median age was 41 years. For every 100 females there were 100.30 males. For every 100 females age 18 and over, there were 98.20 males.

The median income for a household in the county was $32,803, and the median income for a family was $37,930. Males had a median income of $32,504 versus $21,086 for females. The per capita income for the county was $17,263. About 11.90% of families and 15.50% of the population were below the poverty line, including 21.20% of those under age 18 and 10.20% of those age 65 or over.

2010 census

As of the 2010 United States Census, there were 40,877 people, 17,100 households, and 11,591 families living in the county.^[16] The population density was 23.6 inhabitants per square mile (9.1/km²). There were 24,669 housing units at an average density of 14.2 units per square mile (5.5 units/km²).^[17] The racial makeup of the county was 96.0% white, 0.8% American Indian, 0.5% Asian, 0.1% Pacific islander, 0.1% black or African American, 0.4% from other races, and 2.1% from two or more races. Those of Hispanic or Latino origin made up 2.2% of the population.^[16] In terms of ancestry, 25.4% were German, 15.3% were Irish, 15.2% were English, 6.2% were Norwegian, and 5.0% were American.^[18]

Of the 17,100 households, 27.2% had children under the age of 18 living with them, 55.3% were married couples living together, 7.9% had a female householder with no husband present, 32.2% were non-families, and 26.0% of all households were made up of individuals. The average household size was 2.37 and the average family size was 2.82. The median age was 45.8 years.^[16]

The median income for a household in the county was $41,943 and the median income for a family was $51,377. Males had a median income of $40,076 versus $30,829 for females. The per capita income for the county was $24,745. About 10.1% of families and 14.3% of the population were below the poverty line, including 22.3% of those under age 18 and 6.7% of those age 65 or over.^[19]

Cities

Census-designated place

• Blanchard
• Coolin
• Laclede

Unincorporated communities