605 ILCS 5/6-201.11

Cause to be erected and kept in repair at intersections of the most important public roads, guide and direction signs and any other signs authorized by this Code or by the Illinois Vehicle Code.

In unincorporated territory located within counties with a population of more than 3,000,000 inhabitants, the homeowners association of a subdivision with at least 100 permanent dwellings may cause to be erected and kept in repair guide and direction or street signs at intersections within the subdivision. These signs shall be at least 7 feet above the curb and may be on wooden posts with wooden boards. The homeowners association shall be responsible for maintenance and replacement of the signs. Signs shall be located so as not to interfere with pedestrian or vehicular traffic.