In the Nebraska license plate system, Nemaha County is represented by the prefix 44 (it had the forty-fourth-largest number of vehicles registered in the county when the license plate system was established in 1922).
1860 - 3,139 1870 - 7,593 1880 - 10,451 1890 - 12,930 1900 - 14,952 1910 - 13,095 1920 - 12,547 1930 - 12,356 1940 - 12,781 1950 - 10,973 1960 - 9,099 1970 - 8,976 1980 - 8,367 1990 - 7,980 2000 - 7,576
As of the census of 2000, there were 7,576 people, 3,047 households, and 1,980 families residing in the county. The population density was 18 people per square mile (7/km²). There were 3,439 housing units at an average density of 8 per square mile (3/km²). The racial makeup of the county was 97.60% White, 0.36% Black or African American, 0.30% Native American, 0.59% Asian, 0.04% Pacific Islander, 0.37% from other races, and 0.74% from two or more races. 1.00% of the population were Hispanic or Latino of any race.
There were 3,047 households out of which 29.50% had children under the age of 18 living with them, 55.00% were married couples living together, 7.20% had a female householder with no husband present, and 35.00% were non-families. 30.50% of all households were made up of individuals and 16.20% had someone living alone who was 65 years of age or older. The average household size was 2.32 and the average family size was 2.91.
In the county the population was spread out with 23.20% under the age of 18, 11.90% from 18 to 24, 23.90% from 25 to 44, 22.70% from 45 to 64, and 18.40% who were 65 years of age or older. The median age was 39 years. For every 100 females there were 93.30 males. For every 100 females age 18 and over, there were 92.00 males.
The median income for a household in the county was $32,588, and the median income for a family was $43,780. Males had a median income of $30,956 versus $19,263 for females. The per capita income for the county was $17,004. About 8.30% of families and 12.60% of the population were below the poverty line, including 13.20% of those under age 18 and 13.50% of those age 65 or over.