As of the 2010 census, its population was 989 and it contained 409 housing units.

[3] The township was named for John Dement (1804–1883), a politician and militia commander from Illinois.

[4] According to the 2010 census, the township has a total area of 35 square miles (91 km2), of which 34.95 square miles (90.5 km2) (or 99.86%) is land and 0.05 square miles (0.13 km2) (or 0.14%) is water.

[2] It contains the village of Creston, and the east side of the city of Rochelle.

The township contains Woodlawn Cemetery.