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.
Geography
According to the U.S. Census Bureau, the county has a total area of , of which is land and (4.6%) is water.
Adjacent counties
- Henry County (north)
- Benton County (northeast)
- Hickory County (east)
- Polk County (southeast)
- Cedar County (south)
- Vernon County (southwest)
- Bates County (northwest)
Major highways
- 20px U.S. Route 54
- 20px Route 13
- 20px Route 52
- 20px Route 82
Transit
- Jefferson Lines