sentences:  The original boundary of St. Clair county covered a large area between the Mackinaw and Ohio rivers.In 1801, Governor William Henry Harrison re-established St. Clair County as part of the Indiana Territory, extending its northern border to Lake Superior and the international border with Rupert's Land.When the Illinois Territory was created in 1809, Territorial Secretary Nathaniel Pope, in his capacity as acting governor, issued a proclamation establishing St. Clair and Randolph County as the two original counties of Illinois.