 Montgomery Township was organized in 1859.According to the United States Census Bureau, the township has a total area of 34.6 square miles (89.5 km²), of which 33.7 square miles (87.2 km²) of it is land and 0.9 square miles (2.3 km²) of it (2.58%) is water.As of the census of 2000, there were 745 people, 272 households, and 206 families residing in the township.