St. Clair County, Missouri

St. Clair County
St. Clair County courthouse in Osceola
Location within the U.S. state of Missouri
Missouri's location within the U.S.
Coordinates: 38°02′N 93°46′W / 38.04°N 93.77°W / 38.04; -93.77
Country United States
State Missouri
FoundedJanuary 29, 1841
Named afterArthur St. Clair
SeatOsceola
Largest cityAppleton City
Area
  Total
702 sq mi (1,820 km2)
  Land670 sq mi (1,700 km2)
  Water32 sq mi (80 km2)  4.6%
Population
 (2020)
  Total
9,284
  Estimate 
(2024)
9,848
  Density14.7/sq mi (5.7/km2)
Time zoneUTC−6 (Central)
  Summer (DST)UTC−5 (CDT)
Congressional district4th
Websitewww.stclaircomo.com

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.