St. Clair County, founded in the year 1790, was named on the behalf of Arthur St. Clair. It has the county seat in Belleville. With a total area of 674.03 sq mi, it has over 0.27 million people with a rich mix of White, Native American, black or African American, Asian, Hispanic or Latino, Pacific Islander, and others with more than 96.8K households and 67.2K families. It is the oldest county in the United States State of Illinois.

Today the St. Clair County records library is successfully planned with neat, clean and prolific data on land and property deeds, death and obituary including cemetery and burial news, probate records including legal and guardianship documents, birth and census archive, ancestral Social Security Numbers, marriage and divorce decree, military service data, civil records details, World War I & II and American civil wars archive and so on in a more organized technical way than before.