sentences:  Many ethnic and Catholic French moved to settlements west of the river rather than live under British Protestant rule.After the United States achieved independence in the late 18th century, St. Clair County was the first county established in present-day Illinois; it antedates Illinois' existence as a separate jurisdiction.The county was established in 1790 by a proclamation of Arthur St. Clair, first governor of the Northwest Territory, who named it after himself.