 The bank at Shawneetown was the first in Illinois.It was originally in the John Marshall House, which has been rebuilt and serves as the museum of the Gallatin County Historical Society.This should not be confused with the State Bank of Illinois building, which is a state historic site a block away in Old Shawneetown

According to the U.S. Census Bureau, the county has a total area of , of which is land and (1.6%) is water.