According to Warren Upham, the township was probably named for Washington Irving, an American author.

As of the census[1] of 2000, there were 787 people, 310 households, and 243 families residing in the township.

There were 559 housing units at an average density of 17.0 per square mile (6.6/km2).

There were 310 households, out of which 28.7% had children under the age of 18 living with them, 72.6% were married couples living together, 1.9% had a female householder with no husband present, and 21.3% were non-families.

17.7% of all households were made up of individuals, and 5.5% had someone living alone who was 65 years of age or older.