In the Nebraska license plate system, Cheyenne County is represented by the prefix 39 as it had the thirty-ninth-largest number of vehicles registered in the county when the license plate system was established in 1922.
1870 - 190 1880 - 1,558 1890 - 5,693 1900 - 5,570 1910 - 4,551 1920 - 8,405 1930 - 10,187 1940 - 9,505 1950 - 12,081 1960 - 14,828 1970 - 10,778 1980 - 10,057 1990 - 9,494 2000 - 9,830
As of the census of 2000, of 2000, there were 9,830 people, 4,071 households, and 2,686 families residing in the county. The population density was 8 people per square mile (3/km²). There were 4,569 housing units at an average density of 4 per square mile (1/km²). The racial makeup of the county was 96.34% White, 0.14% Black or African American, 0.65% Native American, 0.40% Asian, 0.03% Pacific Islander, 1.46% from other races, and 0.98% from two or more races. 4.46% of the population were Hispanic or Latino of any race. 45.3% were of German, 9.1% English, 7.6% Irish and 7.5% American ancestry according to Census 2000.
There were 4,071 households out of which 31.10% had children under the age of 18 living with them, 54.80% were married couples living together, 8.00% had a female householder with no husband present, and 34.00% were non-families. 30.10% of all households were made up of individuals and 13.30% had someone living alone who was 65 years of age or older. The average household size was 2.38 and the average family size was 2.96.
In the county the population was spread out with 26.30% under the age of 18, 7.00% from 18 to 24, 26.70% from 25 to 44, 22.80% from 45 to 64, and 17.20% who were 65 years of age or older. The median age was 39 years. For every 100 females there were 96.00 males. For every 100 females age 18 and over, there were 92.20 males.
The median income for a household in the county was $33,438, and the median income for a family was $41,024. Males had a median income of $30,000 versus $20,467 for females. The per capita income for the county was $17,437. About 8.20% of families and 10.00% of the population were below the poverty line, including 11.80% of those under age 18 and 7.40% of those age 65 or over.