70 ILCS 1105/23
Any territory adjoining a museum district and situated in the same county as the district may become a part of the district as provided in this Section. Upon the filing with the circuit court of the county in which the district is located of a petition signed by not less than 10% of the legal voters residing within the territory proposed to be annexed, the clerk of the circuit court shall certify the question of the annexation to the proper election officials, who shall submit the question to the voters of the territory proposed to be annexed in accordance with the general election law. If a majority of the votes cast on the question are in favor of the annexation, the territory proposed to be annexed shall then be a part of the museum district.
70 ILCS 1105/23