 Westbound I-70's interchange is exit 15; the exits east of that are numbered as if I-70 had run along I-270 for the first few miles in Illinois.I-70 meets IL Routes 4 and 143 to the south and east of Marine before crossing Highland Silver Lake.US 40 rejoins I-70 near Pierron and the two highways travel concurrently into Bond County, where they separate at Pocahontas.