Ralls County is a county located in the northeastern portion of the U.S. state of Missouri. As of the 2010 census, the population was 10,167. Its county seat is New London. The county was organized November 16, 1820 and named for Daniel Ralls, Missouri state legislator.
According to the U.S. Census Bureau, the county has a total area of 484 square miles (1,250 km), of which 470 square miles (1,200 km) is land and 14 square miles (36 km) (2.9%) is water.
As of the census of 2010, there were 10,167 people, 3,736 households, and 2,783 families residing in the county. The population density was 20 people per square mile (8/km²). There were 4,564 housing units at an average density of 10 per square mile (4/km²). The racial makeup of the county was 97.93% White, 1.11% Black or African American, 0.20% Native American, 0.08% Asian, 0.01% Pacific Islander, 0.04% from other races, and 0.62% from two or more races. Approximately 0.44% of the population were Hispanic or Latino of any race. 30.1% were of American, 27.3% German, 10.5% English and 10.4% Irish ancestry.
There were 3,736 households out of which 34.00% had children under the age of 18 living with them, 64.20% were married couples living together, 6.50% had a female householder with no husband present, and 25.50% were non-families. 21.20% of all households were made up of individuals and 10.00% had someone living alone who was 65 years of age or older. The average household size was 2.55 and the average family size was 2.95.
In the county, the population was spread out with 25.20% under the age of 18, 7.10% from 18 to 24, 26.90% from 25 to 44, 26.50% from 45 to 64, and 14.20% who were 65 years of age or older. The median age was 39 years. For every 100 females, there were 100.90 males. For every 100 females age 18 and over, there were 98.90 males.
The median income for a household in the county was $37,094, and the median income for a family was $41,955. Males had a median income of $28,139 versus $20,238 for females. The per capita income for the county was $16,456. About 6.60% of families and 8.70% of the population were below the poverty line, including 9.70% of those under age 18 and 10.70% of those age 65 or over.