The General Assembly, constituting the Legislature of the State of Illinois, assents to the provisions, terms, conditions and purposes of the Federal Aid Road Act as defined in this Code.
In the location of highways which will be part of the National System of Interstate and Defense Highways referred to in the Federal Aid Highway Act of 1956 ( public law 627 of the 84th Congress), existing highways of the State highway system as defined in this Code shall be used to the extent as the Department finds such use is practicable, suitable and feasible. The selection of such locations shall be made as provided in Section 3--103 of this Code.
605 ILCS 5/3-101