[3] It was named for the ninth US President William Henry Harrison.

[4] Harrison County is included in the Omaha-Council Bluffs, NE-IA Metropolitan Statistical Area.

[13] As of the census[14] of 2000, there were 15,666 people, 6,115 households, and 4,304 families residing in the county.

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.

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.

Only seven Democratic Party candidates have won the county from 1880 to the present, the most recent of whom was Lyndon B. Johnson in 1964.