Sioux County is a county located in the U.S. state of Nebraska. As of 2000, the population is 1,475. Its county seat is Harrison. As of the census2 of 2000, there were 1,475 people, 605 households, and 444 families residing in the county. The population density was 0/km˛ (1/mi˛). There were 780 housing units at an average density of 0/km˛ (0/mi˛). The racial makeup of the county was 97.63% White, 0.14% Native American, 0.20% Asian, 1.15% from other races, and 0.88% from two or more races. 2.31% of the population were Hispanic or Latino of any race.

There were 605 households out of which 28.10% had children under the age of 18 living with them, 65.30% were married couples living together, 5.10% had a female householder with no husband present, and 26.60% were non-families. 23.60% of all households were made up of individuals and 9.40% 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 2.86.