Reiner Township was named for Reinhart Johnsrud, a county official.

[3] According to the United States Census Bureau, the township has a total area of 27.0 square miles (69.8 km2), all land.

As of the census[1] of 2000, there were 94 people, 38 households, and 28 families residing in the township.

There were 38 households, out of which 26.3% had children under the age of 18 living with them, 71.1% were married couples living together, 2.6% had a female householder with no husband present, and 26.3% were non-families.

23.7% of all households were made up of individuals, and 2.6% had someone living alone who was 65 years of age or older.