 Sumter Township was named after Fort Sumter, the American Civil War fort.According to the United States Census Bureau, the township has a total area of 35.8 square miles (92.6 km²), of which 35.0 square miles (90.6 km²) of it is land and 0.8 square miles (2.0 km²) of it (2.18%) is water.As of the census of 2000, there were 558 people, 184 households, and 153 families residing in the township.