 Oak Park Township was organized in 1883, and named for the oak groves within its borders.According to the United States Census Bureau, the township has a total area of 39.3 square miles (101.8 km²), of which 38.9 square miles (100.8 km²) of it is land and 0.4 square miles (1.1 km²) of it (1.07%) is water.As of the census of 2000, there were 165 people, 67 households, and 47 families residing in the township.