St. Clair County is a county located in the western portion of the U.S. state of Missouri. As of the 2020 census, the population was 9,284. Its county seat is Osceola. The largest city is Appleton City. The county was organized in 1841 and named after General Arthur St. Clair, Governor of the Northwest Territory. St. Clair was also the 9th president of the United States in Congress Assembled. Under his presidency, the Northwest Ordinance and United States Constitution were passed.
According to the April 1907 issue of The Century Magazine, for well over 30 years (dating from 1870) St. Clair County was in open rebellion against the U.S. Government, refusing to pay interest on bonds issued to assist in the building of a railroad that was never built.
According to the U.S. Census Bureau, the county has a total area of , of which is land and (4.6%) is water.
As of the 2020 census, the county had a population of 9,284. The median age was 48.4 years, with 21.3% of residents under the age of 18 and 25.8% aged 65 or older. For every 100 females there were 102.7 males, and for every 100 females age 18 and over there were 101.3 males.
The racial makeup of the county was 93.1% White, 0.3% Black or African American, 0.7% American Indian and Alaska Native, 0.2% Asian, 0.1% Native Hawaiian and Pacific Islander, 0.7% from some other race, and 4.9% from two or more races. Hispanic or Latino residents of any race comprised 1.9% of the population.
0.0% of residents lived in urban areas, while 100.0% lived in rural areas.
There were 3,928 households in the county, of which 23.3% had children under the age of 18 living with them and 23.3% had a female householder with no spouse or partner present. About 31.8% of all households were made up of individuals and 17.1% had someone living alone who was 65 years of age or older.
There were 5,288 housing units, of which 25.7% were vacant. Among occupied housing units, 76.0% were owner-occupied and 24.0% were renter-occupied. The homeowner vacancy rate was 1.6% and the rental vacancy rate was 10.7%.
As of the census of 2000, there were 9,652 people, 4,040 households, and 2,791 families residing in the county. The population density was . There were 5,205 housing units at an average density of . The racial makeup of the county was 97.36% White, 0.23% Black or African American, 0.75% Native American, 0.15% Asian, 0.02% Pacific Islander, 0.29% from other races, and 1.21% from two or more races. Approximately 0.98% of the population were Hispanic or Latino of any race.
There were 4,040 households, out of which 26.30% had children under the age of 18 living with them, 57.60% were married couples living together, 7.70% had a female householder with no husband present, and 30.90% were non-families. 27.40% of all households were made up of individuals, and 14.80% had someone living alone who was 65 years of age or older. The average household size was 2.34 and the average family size was 2.83.
In the county, the population was spread out, with 23.00% under the age of 18, 5.60% from 18 to 24, 22.90% from 25 to 44, 27.20% from 45 to 64, and 21.30% who were 65 years of age or older. The median age was 44 years. For every 100 females there were 98.60 males. For every 100 females age 18 and over, there were 94.30 males.
The median income for a household in the county was $25,321, and the median income for a family was $31,498. Males had a median income of $23,231 versus $18,351 for females. The per capita income for the county was $14,025. About 16.20% of families and 19.60% of the population were below the poverty line, including 25.30% of those under age 18 and 17.60% of those age 65 or over.
St. Clair County is divided into 16 townships:
The Republican Party predominantly controls politics at the local level in St. Clair County.
All of St. Clair County is a part of Missouri's 125th District in the Missouri House of Representatives and is represented by Warren Love (R-Osceola).
All of St. Clair County is a part of Missouri's 28th District in the Missouri Senate. The seat is currently Held by Sandy Crawford.
All of St. Clair County is included in Missouri's 4th Congressional District and is currently represented by Vicky Hartzler (R-Harrisonville) in the U.S. House of Representatives.