70 ILCS 5/9.1
Any territory which is not within the corporate limits of any airport authority but which is contiguous to an airport authority and which territory has no electors residing therein, or any such territory with electors residing thereon, may be annexed to the airport authority in one of the following ways: (1) a written petition, which may be initiated by an ordinance adopted by the board, signed by a majority of the owners of record of all land within such territory, or if such territory is occupied, by a majority of the owners of record and by a majority of electors residing thereon, shall be filed with the Board, which petition shall request annexation and shall state that no electors reside thereon (or that a majority of the electors residing thereon join in the petition, whichever shall be the case) and shall be under oath. The Board of the airport authority to which annexation is sought shall then consider the question of the annexation of the described territory. A majority vote of the Board is required to annex. The vote shall be by "ayes" and "noes" entered on the Board records. A copy of the Board resolution annexing the territory together with an accurate map of the annexed territory shall be recorded with the recorder within the county wherever the annexed territory is located; (2) a written petition, which may be initiated by an ordinance adopted by the Board, signed by at least 10% of the owners of record of all land within the territory, or if the territory is occupied, by at least 10% of the owners of record of all land within the territory and 10% of all electors residing thereon, shall be filed with the clerk of the circuit court of the county in which the district or the greater portion of it is located. A hearing shall be held on the petition. If upon the hearing the circuit court finds that the petition is in compliance with law, the court shall order a proposition to be submitted to the electors at a referendum to decide if the proposed annexation shall take place. The clerk of the court shall certify the order and the proposition to the proper election officials, who shall submit the proposition to the electors at an election in accordance with the general election law. The proposition shall be submitted within the territory as provided in Section 2.3 of this Act. The proposition shall be substantially in the following form:
------------------------------------------------------------------------ Shall (description of YES territory) be annexed to the ----------------------------------------- ...... Airport Authority? NO ------------------------------------------------------------------------
If a majority of the electors voting on the proposition vote for annexation and if the board accepts the proposed addition by an ordinance annexing the land, the circuit court shall enter an appropriate order and the annexed land shall thereafter be considered part of the airport authority.
70 ILCS 5/9.1