St. Clair County is the name of four counties in the United States:
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St. Clair County, Alabama
St. Clair County is a county located in the central portion of the U.S. state of Alabama."ACES Winston County Office" (links/history), Alabama Cooperative Extension System (ACES), 2007, webpageACES-St.Clair As of the 2020 census, the populatio ...
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St. Clair County, Illinois
St. Clair County is the oldest county in Illinois; its western border is formed by the Mississippi River, bordering Missouri. It is a part of the Metro East in southern Illinois. At the 2020 United States census, it had a population of 257,400 ...
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St. Clair County, Michigan
St. Clair County is a county located in the U.S. state of Michigan and bordering the west bank of the St. Clair River. As of the 2020 Census, the population was 160,383. It is the 13th-most populous county in the state. The county seat is Port ...
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St. Clair County, Missouri
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 n ...
{{geodis, uscounty