225 ILCS 440/4.05
Signs in existence in a "business area", except signs which do not comply with Section 5, subsection (b) of Section 6.02, subsection (a) of Section 6.03 or Section 8 of this Act. For purposes of this Section, to be "in existence" the supports and frame of a sign must be physically in place: (a) on the effective date of this Act; or (b) on the date subsequent to the passage of this Act when the area in which the sign is located becomes subject to this Act or within six months thereafter, provided the sign is located on property leased prior to the date the area becomes subject to this Act and a copy of the lease is filed with the Department within 30 days following such date, except that the six month period shall not apply to those portions of a highway constructed on new alignment.
225 ILCS 440/4.05