Smithton Township (Township 1 South, Range 8 West) is located in St. Clair County, Illinois. As of the 2010 census, its population was 4,275 and it contained 1,684 housing units.
According to the 2010 census, the township has a total area of , of which (or 98.09%) is land and (or 1.91%) is water.
The current Members of the Smithton Township Board are Supervisor William F. Weber; Trustees Donald Barkau, Mark Rodriguez, Neil Espenschied, Quentin Grommet; Highway Commissioner Paul Reinneck; Clerk Troy L. Herring.
All seven Smithton Township Officials are serving a four-year term that ends in May, 2025.