Major highways

• U.S. Highway 30
• Iowa Highway 4
• Iowa Highway 25
• Iowa Highway 144

Adjacent counties

• Calhoun County (northwest)
• Webster County (northeast)
• Boone County (east)
• Dallas County (southeast)
• Guthrie County (south)
• Carroll County (west)

2020 census

The 2020 census recorded a population of 8,771 in the county, with a population density of 15.3492/sq mi (5.9264/km²). 96.21% of the population reported being of one race. 91.23% were non-Hispanic White, 0.32% were Black, 2.92% were Hispanic, 0.18% were Native American, 0.57% were Asian, 0.01% were Native Hawaiian or Pacific Islander and 4.77% were some other race or more than one race. There were 4,309 housing units, of which 3,802 were occupied.^[1]

2010 census

The 2010 census recorded a population of 9,336 in the county, with a population density of 16.4248/sq mi (6.3416/km²). There were 4,546 housing units, of which 3,996 were occupied.^[12]

2000 census

As of the census^[13] of 2000, there were 10,366 people, 4,205 households, and 2,859 families residing in the county. The population density was 18 people per square mile (6.9 people/km²). There were 4,623 housing units at an average density of 8 units per square mile (3.1 units/km²). The racial makeup of the county was 98.16% White, 0.14% Black or African American, 0.15% Native American, 0.24% Asian, 0.01% Pacific Islander, 0.67% from other races, and 0.63% from two or more races. 1.66% of the population were Hispanic or Latino of any race.

There were 4,205 households, out of which 30.70% had children under the age of 18 living with them, 57.30% were married couples living together, 7.20% had a female householder with no husband present, and 32.00% were non-families. 29.10% of all households were made up of individuals, and 16.60% had someone living alone who was 65 years of age or older. The average household size was 2.41 and the average family size was 2.97.

In the county, the population was spread out, with 25.60% under the age of 18, 6.10% from 18 to 24, 24.30% from 25 to 44, 22.40% from 45 to 64, and 21.60% who were 65 years of age or older. The median age was 41 years. For every 100 females there were 95.50 males. For every 100 females age 18 and over, there were 89.20 males.

The median income for a household in the county was $33,883, and the median income for a family was $41,230. Males had a median income of $29,076 versus $21,657 for females. The per capita income for the county was $16,866. About 4.80% of families and 8.10% of the population were below the poverty line, including 8.90% of those under age 18 and 7.80% of those age 65 or over.

Unincorporated community

• Cooper

Townships

Population ranking

The population ranking of the following table is based on the 2020 census of Greene County.^[1]

† county seat