(605 ILCS 5/2-101) (from Ch. 121, par. 2-101)
    Sec. 2-101. The State highway system includes the following rural highways together with their municipal extensions except those not designated by a State highway route number and for which an agreement initiated by a local authority has been executed between the Department and the local authority providing for other jurisdictional responsibility:
        (a) Highways constructed under the provisions of "An Act in relation to the construction
    
by the State of Illinois of a state-wide system of durable hard surfaced roads upon public highways, of the State and the provision of means for the payment of the cost thereof by an issue of bonds of the State of Illinois", approved June 22, 1917, and under the provisions of "An Act in relation to the construction by the State of Illinois, of durable hard surfaced roads upon public highways of the State along designated routes, and the provision of means for the payment of the cost thereof by an issue of bonds of the State of Illinois", approved June 29, 1923;
        (b) Highways constructed by the State as federal aid interstate highways or federal aid
    
primary highways under the provisions of "An Act in relation to the construction and maintenance of Federal-aid roads under and in accordance with an Act of Congress entitled, 'An Act to provide that the United States shall aid the states in the construction of rural post roads, and for other purposes', approved July 11, 1916, and known as the Federal Aid Road Act, as heretofore or hereafter amended by Congress and all Acts supplemental thereto", approved June 27, 1917, as amended.
        (c) Highways constructed as federal aid secondary highways under the provisions of
    
Section 11a of "An Act in relation to State highways", approved June 24, 1921, as amended, and for which maintenance responsibility has not been delegated to a county pursuant to an agreement between the Department and a county under the provisions of that Act.
        (d) Highways constructed as State aid roads under the provisions of "An Act to revise
    
the law in relation to roads and bridges", approved June 27, 1913, as amended, and accepted by the Department for maintenance under the provisions of Section 32 of that Act;
        (e) Highways constructed under the provisions of Section 9 of the "Motor Fuel Tax Law",
    
approved March 25, 1929, as amended, which the Department was directed to maintain by such Section 9;
        (f) Highways constructed by the Department under the provisions of authority granted by
    
any Act of the General Assembly prior to the effective date of this Code;
        (g) Highways on which construction is completed after the effective date of this Code
    
and which under the provisions of this Code become a part of the State highways system;
        (h) Highways added to the State Highway system under the provisions of this Code.
(Source: Laws 1967, p. 3065.)