In Belleville I overnighted at the Super 8 and the next morning took the Metro-Link to Lambert Field from where I rode across the Page bridge and picked up the KATY.
I was fortunate to have a strong south wind and made the 86 miles from Harrisburg to Belleville in an easy day's ride. Generally wide shoulders on IL 13. Because of the south wind I went north on US 51 at Carbondale and worked my way west to IL 13.
One could also follow the ACA route to Murhysboro and pick up IL 13 there.