Illinois Route 142 is a diagonal northwest-southeast route in southern and southeastern Illinois. It begins in Mount Vernon and heads southeast through McLeansboro and Eldorado to end in the town of Equality, just south of Illinois 13. It's signed as a north-south highway.
Illinois 142 enters McLeansboro and splits into two separate one-way streets, where it meets Illinois 242:
The southern end of Illinois 142's stint as a pair of one-way streets in McLeansboro is at Illinois 14. In an odd situation, the southbound path of Illinois 142 joins Illinois 14 east for one block to converge back into a single route carrying both directions of traffic. This creates a short concurrency eastbound for the southbound traffic, but creates no concurrency for northbound traffic, which crosses straight northward through the junction with Illinois 14:
At Eldorado, Illinois 142 heads southeast crossing the northeast-southwest US Route 45:
North of Equality, Illinois 142 crosses Illinois 13, and continues south into Equality:
Illinois 142 ends at no state-maintained highway, but it reaches Equality, ending there, where drivers can continue south toward Garden of the Gods Recreation Area, my favorite place to hike in the state of Illinois: