In the Nebraska license plate system, Frontier County is represented by the prefix 60 (it had the sixtieth-largest number of vehicles registered in the county when the license plate system was established in 1922).
1880 - 934 1890 - 8,497 1900 - 8,781 1910 - 8,572 1920 - 8,540 1930 - 8,114 1940 - 6,417 1950 - 5,282 1960 - 4,311 1970 - 3,982 1980 - 3,647 1990 - 3,101 2000 - 3,099
As of the census of 2000, there were 3,099 people, 1,192 households, and 828 families residing in the county. The population density was 3 people per square mile (1/km²). There were 1,543 housing units at an average density of 2 per square mile (1/km²). The racial makeup of the county was 98.29% White, 0.10% Black or African American, 0.26% Native American, 0.26% Asian, 0.39% from other races, and 0.71% from two or more races. 0.97% of the population were Hispanic or Latino of any race. 45.8% were of German, 12.8% English, 6.3% American and 6.1% Irish ancestry according to Census 2000.
There were 1,192 households out of which 31.40% had children under the age of 18 living with them, 62.50% were married couples living together, 4.80% had a female householder with no husband present, and 30.50% were non-families. 26.30% of all households were made up of individuals and 12.30% had someone living alone who was 65 years of age or older. The average household size was 2.48 and the average family size was 3.02.
In the county the population was spread out with 26.00% under the age of 18, 11.30% from 18 to 24, 22.80% from 25 to 44, 23.00% from 45 to 64, and 16.90% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 100.50 males. For every 100 females age 18 and over, there were 98.50 males.
The median income for a household in the county was $33,038, and the median income for a family was $38,664. Males had a median income of $25,792 versus $16,941 for females. The per capita income for the county was $16,648. About 9.30% of families and 12.20% of the population were below the poverty line, including 9.90% of those under age 18 and 8.30% of those age 65 or over.