Illinois Route 126 is a short east-west route from Yorkville to Plainfield, in Kendall County and western Will County. Its eastern segment is a connector, stemming from Plainfield northeasterly to Interstate 55 toward or away from Chicago.
The western end of Illinois 126 is at Illinois 47 in downtown Yorkville:
As Illinois 126 exits Yorkville heading east, it crosses Illinois 71:
In Plainfield, Illinois 126 turns onto a northeasterly-oriented "Main Street":
Finally, Illinois 126 ends at a partial interchange with Interstate 55, where you can connect with that route only heading toward or from the northeast. This provides a seamless connection between Plainfield and Chicago.
Here's a closeup of the Interstate 55 marker in the background of the above photo, indicating that only the northbound lanes of Interstate 55 can be accessed from here: