[3] Decoria Township, organized in 1867, was named for a Winnebago chieftain.

As of the census[1] of 2000, the township had 922 people, 329 households, and 273 families.

The population density was 25.7 people per square mile (9.9/km2).

There were 329 households, of which 38.0% had children under the age of 18 living with them, 76.0% were married couples living together, 4.3% had a female householder with no husband present, and 17.0% were non-families.

11.9% of all households were made up of individuals, and 6.4% had someone living alone who was 65 years of age or older.