The 2010 census recorded a population of 14,928 in the county, with a population density of. There were 6,731 housing units, of which 5,987 were occupied.
2000 census
As of the census of 2000, there were 15,666 people, 6,115 households, and 4,304 families residing in the county. The population density was 22 people per square mile. There were 6,602 housing units at an average density of 10 per square mile. The racial makeup of the county was 98.69% White, 0.08% Black or African American, 0.22% Native American, 0.16% Asian, 0.01% Pacific Islander, 0.20% from other races, and 0.64% from two or more races. 0.72% of the population were Hispanic or Latino of any race. There were 6,115 households out of which 32.30% had children under the age of 18 living with them, 59.30% were married couplesliving together, 7.60% had a female householder with no husband present, and 29.60% were non-families. 26.10% of all households were made up of individuals and 13.70% had someone living alone who was 65 years of age or older. The average household size was 2.51 and the average family size was 3.02. In the county, the population was spread out with 26.20% under the age of 18, 6.80% from 18 to 24, 27.00% from 25 to 44, 22.30% from 45 to 64, and 17.70% who were 65 years of age or older. The median age was 39 years. For every 100 females there were 96.50 males. For every 100 females age 18 and over, there were 91.80 males. The median income for a household in the county was $38,141, and the median income for a family was $44,586. Males had a median income of $30,000 versus $21,663 for females. The per capita income for the county was $17,662. About 5.00% of families and 7.10% of the population were below the poverty line, including 8.70% of those under age 18 and 8.70% of those age 65 or over.
The population ranking of the following table is based on the 2010 census of Harrison County. †county seat
Rank
City/Town/etc.
Municipal type
Population
1
Missouri Valley
City
2,838
2
†Logan
City
1,534
3
Woodbine
City
1,459
4
Dunlap
City
1,042
5
Mondamin
City
402
6
Persia
City
319
7
Modale
City
283
8
Pisgah
City
251
9
Magnolia
City
183
10
Little Sioux
City
170
11
California Junction
CDP
85
12
River Sioux
CDP
59
Politics
Harrison County is strongly Republican in presidential elections. Only seven Democratic Party candidates have won the county from 1896 to the present, the most recent of which being Lyndon B. Johnson in 1964.
