The first section of unbannered route stretches from Chester to near Fall Creek. It begins at the approach to the Chester Bridge, following IL 150 and the remainder of the truck bypass back to IL 3, which carries the Great River Road all the way to East St. Louis. But instead of continuing along IL 3 through the riverside industrial areas, the route turns east on I-55 / I-70, north on IL 111, and back west on I-270 to rejoin IL 3 in Granite City. It soon leaves IL 3 for the last time to follow IL 143 into downtown Alton and then a short piece of US 67 to reach IL 100, which runs directly along the river for a significant distance before turning inland at Grafton. Rather than cross the Illinois River on the Brussels Ferry, the Great River Road remains with IL 100 alongside the Illinois River, first on the east side to the Hardin Bridge and then on the west side to Kampsville. There it turns west to rejoin the Mississippi River, following IL 96 to north of Hull and former IL 57 to the I-172 interchange near Fall Creek.