65 ILCS 5/7-1-7

(a) If the court finds that an annexation ordinance is valid, the court shall enter an order directing the submission of the question of annexation of the unincorporated territory to the electors of that territory at an election in accordance with the general election law and directing the clerk of the annexing municipality to send, by registered mail, a notice of the date of the prospective referendum to the highway commissioner of each road district within which the territory proposed to be annexed is situated. The clerk of the circuit court shall certify the question for submission.

(b) If a majority of those casting ballots favor annexation, the described territory shall, except as otherwise provided in Section 7-1-1, thereupon be a part of the annexing municipality. Within 15 days after the referendum, the clerk of the annexing municipality shall promptly send written notice of the results of the referendum by registered mail to the highway commissioner of each road district within which the territory is situated.

(c) If a municipal clerk fails to send any notice to a highway commissioner as required by this Section, the municipality shall reimburse the road district served by that highway commissioner for any loss or liability caused by that failure.