Ellsworth Township was organized in 1868, and named for Colonel Elmer E. Ellsworth, friend of Abraham Lincoln, often called the "first conspicuous casualty" of the Civil War.

As of the census[1] of 2000, there were 854 people, 328 households, and 267 families residing in the township.

There were 460 housing units at an average density of 15.6 per square mile (6.0/km2).

There were 328 households, out of which 32.6% had children under the age of 18 living with them, 75.0% were married couples living together, 3.0% had a female householder with no husband present, and 18.3% were non-families.

15.2% of all households were made up of individuals, and 6.1% had someone living alone who was 65 years of age or older.