In 1802, Spain returned most of the land to France, but keeping title to about 7,500 square miles. In 1803, most of the land for modern day Kansas was acquired by the United States from France as part of the 828,000 square mileLouisiana Purchase for 2.83 cents per acre. In 1854, the Kansas Territory was organized, then in 1861 Kansas became the 34th U.S. state. In 1855, Nemaha County was established. The first railroad in Nemaha County was built in 1866. On May 30, 1879, the "Irving, Kansas Tornado" passed through Nemaha county. This tornado measured F4 on the Fujita scale, and had a damage path wide and long. Eighteen people were killed and sixty were injured in this tornado.
Geography
According to the U.S. Census Bureau, the county has a total area of, of which is land and is water.
As of the census of 2000, there were 10,717 people, 3,959 households, and 2,763 families residing in the county. The population density was 15 people per square mile. There were 4,340 housing units at an average density of 6 per square mile. The racial makeup of the county was 98.35% White, 0.49% Black or African American, 0.23% Native American, 0.10% Asian, 0.06% Pacific Islander, 0.17% from other races, and 0.60% from two or more races. 0.71% of the population were Hispanic or Latino of any race. There were 3,959 households out of which 34.00% had children under the age of 18 living with them, 61.90% were married couplesliving together, 5.10% had a female householder with no husband present, and 30.20% were non-families. 28.00% of all households were made up of individuals and 16.00% had someone living alone who was 65 years of age or older. The average household size was 2.58 and the average family size was 3.20. In the county, the population was spread out with 28.50% under the age of 18, 6.00% from 18 to 24, 24.10% from 25 to 44, 19.40% from 45 to 64, and 22.00% who were 65 years of age or older. The median age was 39 years. For every 100 females there were 97.00 males. For every 100 females age 18 and over, there were 95.10 males. The median income for a household in the county was $34,296, and the median income for a family was $41,838. Males had a median income of $28,879 versus $19,340 for females. The per capita income for the county was $17,121. About 6.50% of families and 9.10% of the population were below the poverty line, including 9.90% of those under age 18 and 8.50% of those age 65 or over.
Nemaha County was a prohibition, or "dry", county until the Kansas Constitution was amended in 1986 and voters approved the sale of alcoholic liquor by the individual drink with a 30% food sales requirement.
Nemaha County is divided into twenty townships. The cities of Sabetha and Seneca are considered governmentally independent and are excluded from the census figures for the townships. In the following table, the population center is the largest city included in that township's population total, if it is of a significant size.