Illinois 41 begins at a junction with U.S. Route 136 in eastern McDonough County, east of Macomb and north of Adair.

[4] The highway enters St. Augustine in southern Knox County, intersecting Illinois 116 along the village's northern edge.

The Y in reference to an interchange road architecture historically used on Illinois state routes.

through an industrial section between the former Santa Fe mainline to the north and the former CB&Q connector to the south.

IL-41 now proceeds north on an upgraded and wider Linwood Road to West Main Street Illinois Route 164 where it terminates at the nearby access interchange for U.S. 34.