Maries County is a county located in Central Missouri in the United States. As of the 2010 census, the population was 9,176. Its county seat is Vienna. The county was organized March 2, 1855 and named for the Maries River and Little Maries River. 'Maries' is derived from the French marais, which means marsh, lake or pond.
According to the 2000 U.S. Census, the county has a total area of 529.97 square miles (1,372.6 km2), of which 527.73 square miles (1,366.8 km2) (or 99.58%) is land and 2.25 square miles (5.8 km2) (or 0.42%) is water.
As of the census of 2000, there were 8,903 people, 3,519 households, and 2,502 families residing in the county. The population density was 17 people per square mile (7/km²). There were 4,149 housing units at an average density of 8 per square mile (3/km²). The racial makeup of the county was 97.43% White, 0.33% Black or African American, 0.55% Native American, 0.11% Asian, 0.35% from other races, and 1.24% from two or more races. Approximately 1.16% of the population were Hispanic or Latino of any race.
There were 3,519 households out of which 31.60% had children under the age of 18 living with them, 59.00% were married couples living together, 7.70% had a female householder with no husband present, and 28.90% were non-families. 25.70% 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 2.51 and the average family size was 3.00.
In the county the population was spread out with 26.00% under the age of 18, 7.30% from 18 to 24, 26.50% from 25 to 44, 24.50% from 45 to 64, and 15.60% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 101.20 males. For every 100 females age 18 and over, there were 97.90 males.
The median income for a household in the county was $31,925, and the median income for a family was $39,187. Males had a median income of $28,524 versus $20,705 for females. The per capita income for the county was $15,662. About 10.10% of families and 13.10% of the population were below the poverty line, including 17.30% of those under age 18 and 13.20% of those age 65 or over.