70 ILCS 1205/3-9
Whenever any territory, containing 80 acres or less, not incorporated within a park district is wholly bounded by one or more park districts, or is wholly bounded by one or more park districts and a river, lake, railroad or arterial street, such territory may be annexed by any park district by which it is bounded in whole or in part, by the passage of an ordinance to that effect after notice is given as provided in this Section The corporate authorities shall cause notice, stating that annexation of the territory described in the notice is contemplated under this Section, to be published once, in a newspaper published in the annexing park district, or, if no newspaper is published in the annexing park district, then in a newspaper with a general circulation within the annexing park district not more than 45 nor less than 30 days before the passage of the annexation ordinance. The ordinance shall describe the territory annexed and a certified copy thereof together with an accurate map of the annexed territory shall be filed in the offices of the County Clerk and Recorder of each county in which said annexation takes place.
As used in this Section, "arterial street" means any U.S. or State numbered route, controlled access highway, or other major radial or circumferential street or highway designated by local authorities within their respective jurisdictions as part of a major arterial system of streets or highways.
70 ILCS 1205/3-9