Adjacent counties

• Polk County (northwest)
• Marion County (north)
• Jefferson County (east)
• Deschutes County (southeast)
• Lane County (south)
• Benton County (west)

National protected area

• Willamette National Forest (part)

2020 census

As of the 2020 census, there were 128,610 people, the racial makeup of the county was 81% non-Hispanic white, .5% African American, 1% Native American, 1.1% Asian, 5.9% of two or more races, and 9.8% Hispanic.

2010 census

As of the 2010 census, there were 116,672 people, 45,204 households, and 30,976 families living in the county.^[11] The population density was 50.9 inhabitants per square mile (19.7/km²). There were 48,821 housing units at an average density of 21.3 units per square mile (8.2 units/km²).^[12] The racial makeup of the county was 90.6% white, 1.3% American Indian, 1.0% Asian, 0.5% black or African American, 0.1% Pacific islander, 3.3% from other races, and 3.3% from two or more races. Those of Hispanic or Latino origin made up 7.8% of the population.^[11] In terms of ancestry, 22.9% were German, 14.1% were English, 12.7% were Irish, and 7.1% were American.^[13]

Of the 45,204 households, 32.1% had children under age 18 living with them, 52.1% were married couples living together, 11.2% had a female householder with no husband present, 31.5% were non-families, and 24.4% of all households were made up of individuals. The average household size was 2.55 and the average family size was 3.01. The median age was 39.2 years.^[11]

The median income for a household in the county was $45,832 and the median income for a family was $55,320. Males had a median income of $44,450 versus $32,055 for females. The per capita income for the county was $22,165. About 11.0% of families and 15.6% of the population were below the poverty line, including 23.0% of those under age 18 and 7.8% of those age 65 or over.^[14]

2000 census

As of the 2000 census, there were 103,069 people, 39,541 households, and 28,232 families living in the county. The population density was 45 people per square mile (17 people/km²). There were 42,521 housing units at an average density of 19 units per square mile (7.3/km²). The racial makeup of the county was 93.20% White, 0.32% Black or African American, 1.27% Native American, 0.78% Asian, 0.15% Pacific Islander, 1.80% from other races, and 2.49% from two or more races. 4.38% of the population were Hispanic or Latino of any race. 22.2% were of German, 13.0% American, 11.2% English and 8.6% Irish ancestry.

There were 39,541 households, out of which 32.00% had children under the age of 18 living with them, 56.90% were married couples living together, 10.00% had a female householder with no husband present, and 28.60% were non-families. 23.00% of all households were made up of individuals, and 10.10% had someone living alone who was 65 years of age or older. The average household size was 2.58 and the average family size was 3.01.

In the county, the population was spread out, with 26.00% under the age of 18, 8.40% from 18 to 24, 27.00% from 25 to 44, 24.10% from 45 to 64, and 14.50% who were 65 years of age or older. The median age was 37 years. For every 100 females there were 97.50 males. For every 100 females age 18 and over, there were 95.00 males.

The median income for a household in the county was $37,518, and the median income for a family was $44,188. Males had a median income of $35,586 versus $24,073 for females. The per capita income for the county was $17,633. About 8.90% of families and 11.40% of the population were below the poverty line, including 14.80% of those under age 18 and 7.10% of those age 65 or over.

Cities

Census-designated places

Unincorporated communities

• Calapooia
• Foster
• Fox Valley
• Jordan
• Kingston
• Marion Forks
• Riverside
• Santiam Junction
• Berlin