Following the intersection with US 34, US 12/20/45 passes through La Grange Park (as La Grange Road), moving in a slight northwesterly direction. After passing over Salt Creek, US 12/20/45 intersects with Cermak Road/22nd Street in Westchester and is known as Mannheim Road north of this intersection. Mannheim Road, as US 12/20/45 serves as the Eastern starting point for Illinois Route 38 (Roosevelt Road) in Hillside, has a full interchange with Interstate 290, also in Hillside, and serves as the Eastern starting point for Illinois Route 56 (briefly Washington Boulevard in Bellwood, before becoming Butterfield Road).