(625 ILCS 5/1-126.1)
    Sec. 1-126.1. Highway Designations. The Department of Transportation may designate streets or highways in the system of State highways as follows:
        (a) Class I highways include interstate highways,
expressways, tollways, and other highways deemed appropriate by the department.
        (b) Class II highways include major arterials not
built to interstate highway standards that have at least 11 feet lane widths.
        (c) Class III highways include those State highways
that have lane widths of less than 11 feet.
        (d) Non-designated highways are highways in the
system of State highways not designated as Class I, II, or III, or local highways which are part of any county, township, municipal, or district road system. Local authorities also may designate Class II or Class III highways within their systems of highways.
(Source: P.A. 92-417, eff. 1-1-02.)