There were 10,374 households out of which 31.20% had children under the age of 18 living with them, 58.00% were married couples living together, 7.80% had a female householder with no husband present, and 31.20% were non-families. 26.70% of all households were made up of individuals and 11.80% had someone living alone who was 65 years of age or older. The average household size was 2.44 and the average family size was 2.95. In the county, the population was spread out with 24.80% under the age of 18, 8.40% from 18 to 24, 27.10% from 25 to 44, 23.30% from 45 to 64, and 16.40% who were 65 years of age or older. The median age was 39 years. For every 100 females there were 95.90 males. For every 100 females age 18 and over, there were 91.70 males. The median income for a household in the county was $40,763, and the median income for a family was $49,346. Males had a median income of $32,504 versus $23,838 for females. The per capita income for the county was $19,943. About 4.50% of families and 7.60% of the population were below the poverty line, including 8.00% of those under age 18 and 5.90% of those age 65 or over. The population ranking of the following table is based on the 2010 census of Boone County.  † "county seat"  Prior to 1932, Boone County was primarily Republican in presidential elections, aside from 1912 when the county backed Bull Moose candidate & former Republican President Theodore Roosevelt. From 1932 to 1980, the county was a swing county, voting for the national winner in all elections in that period aside from 1960. From 1984 to 2012, the county was consistently Democratic in presidential elections, but swung hard in 2016 by 20.7 points to back Republican Donald Trump similar to many other counties in Iowa.