O'Fallon Township, St. Clair County, Illinois

O'Fallon Township is located in St. Clair County, Illinois. As of the 2010 census, its population was 26,053 and it contained 10,338 housing units.

Geography
According to the 2010 census, the township has a total area of 35.78 sqmi, of which 35.12 sqmi (or 98.16%) is land and 0.66 sqmi (or 1.84%) is water.