Sullivan Township is located in Livingston County, Illinois. As of the 2010 census, its population was 724 and it contained 354 housing units. Sullivan Township formed from Saunemin Township in 1863.
According to the 2010 census, the township has a total area of 41.28 square miles (106.9 km2), all land.
- ^ a b "Population, Housing Units, Area, and Density: 2010 - County -- County Subdivision and Place -- 2010 Census Summary File 1". United States Census. Retrieved 2013-05-28.
Coordinates: 40°53′06″N 88°17′28″W / 40.88500°N 88.29111°W