Rock Island Arsenal is a census-designated place (CDP) in Rock Island County, Illinois, United States.

As of the census[3] of 2000, there were 145 people, 43 households, and 40 families residing in the CDP.

There were 43 housing units at an average density of 27.0 per square mile (10.4/km2).

There were 43 households, out of which 79.1% had children under the age of 18 living with them, 88.4% were married couples living together, 4.7% had a female householder with no husband present, and 4.7% were non-families.

4.7% of all households were made up of individuals, and none had someone living alone who was 65 years of age or older.