Otoe County lies on the east side of Nebraska. Its east boundary line abuts the west boundary lines of the states of Iowa and Missouri. The terrain of Otoe County consists of rolling hills which drop down to the river basin, and rich soil. The area is largely devoted to agriculture. The county has a total area of, of which is land and is water. Otoe County derives its name from the Otoe Indians, who lived in the area.
As of the 2000 United States Census there were 15,396 people, 6,060 households, and 4,229 families in the county. The population density was 25 people per square mile. There were 6,567 housing units at an average density of 11 per square mile. The racial makeup of the county was 97.42% White, 0.29% Black or African American, 0.22% Native American, 0.25% Asian, 0.03% Pacific Islander, 1.14% from other races, and 0.65% from two or more races. 2.45% of the population were Hispanic or Latino of any race. There were 6,060 households out of which 32.50% had children under the age of 18 living with them, 59.70% were married couplesliving together, 7.20% had a female householder with no husband present, and 30.20% were non-families. 26.40% of all households were made up of individuals and 14.10% 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 3.01. The county population contained 26.30% under the age of 18, 6.40% from 18 to 24, 26.10% from 25 to 44, 22.80% from 45 to 64, and 18.30% who were 65 years of age or older. The median age was 40 years. For every 100 females there were 96.20 males. For every 100 females age 18 and over, there were 91.80 males. The median income for a household in the county was $37,302, and the median income for a family was $45,295. Males had a median income of $30,682 versus $21,520 for females. The per capita income for the county was $17,752. About 5.90% of families and 8.10% of the population were below the poverty line, including 9.30% of those under age 18 and 7.70% of those age 65 or over.
Otoe County voters have been very Republican since World War II, like all rural Nebraska counties. In no presidential election has the county supported the Democratic nominee since voting in 1932 for Franklin Delano Roosevelt.
