Sufjan Stevens' Illinois by FlaxmanR

Question 6

Track 11 on the album is an instrumental piece titled “To the Workers of the _____ River Valley Region, I Have an Idea Concerning Your Predicament.” The name of WHAT RIVER, which rises in Wisconsin, flows through multiple Illinois municipalities which take their names from it, and empties into the Mississippi just south of the Quad Cities, fills in this blank?

ROCK River