The town of Rock Valley was platted in 1879 by a Colonel Ira Warren, a Civil War veteran, and the Chicago Milwaukee & St. Paul Railway on ground owned by Warren.

[5] The Rock Valley Community School District Serves the town and the surrounding area.

As of the census of 2020,[8] there were 4,059 people, 1,469 households, and 1,019 families residing in the city.

There were 1,555 housing units at an average density of 348.6 per square mile (134.6/km2).

Hispanic or Latino persons of any race comprised 21.4% of the population.

There were 1,356 housing units at an average density of 421.1 per square mile (162.6/km2).

28.8% of all households were made up of individuals, and 13.5% had someone living alone who was 65 years of age or older.

There were 1,202 housing units at an average density of 711.7 per square mile (274.8/km2).

30.9% of all households were made up of individuals, and 16.5% had someone living alone who was 65 years of age or older.