In the Nebraska license plate system, Butler County is represented by the prefix 25 (it had the twenty-fifth-largest number of vehicles registered in the county when the license plate system was established in 1922).
1860 - 27 1870 - 1,290 1880 - 9,194 1890 - 15,454 1900 - 15,703 1910 - 15,403 1920 - 14,606 1930 - 14,410 1940 - 13,106 1950 - 11,432 1960 - 10,312 1970 - 9,461 1980 - 9,330 1990 - 8,601 2000 - 8,767
As of the census of 2000, there were 8,767 people, 3,426 households, and 2,350 families residing in the county. The population density was 15 people per square mile (6/km²). There were 3,901 housing units at an average density of 7 per square mile (3/km²). The racial makeup of the county was 98.38% White, 0.10% Black or African American, 0.13% Native American, 0.13% Asian, 0.06% Pacific Islander, 0.81% from other races, and 0.40% from two or more races. 1.65% of the population were Hispanic or Latino of any race. 33.1% were of German and 32.0% Czech ancestry according to Census 2000.
There were 3,426 households out of which 33.00% had children under the age of 18 living with them, 59.90% were married couples living together, 5.70% had a female householder with no husband present, and 31.40% were non-families. 28.30% of all households were made up of individuals and 14.40% had someone living alone who was 65 years of age or older. The average household size was 2.53 and the average family size was 3.13.
In the county the population was spread out with 27.90% under the age of 18, 6.60% from 18 to 24, 25.30% from 25 to 44, 22.50% 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 104.10 males. For every 100 females age 18 and over, there were 101.20 males.
The median income for a household in the county was $36,331, and the median income for a family was $44,441. Males had a median income of $28,856 versus $20,979 for females. The per capita income for the county was $16,394. About 4.80% of families and 8.20% of the population were below the poverty line, including 9.80% of those under age 18 and 9.40% of those age 65 or over.