70 ILCS 5/3.4
All initial appointments of commissioners shall be made within twenty days after the determination of the result of said election, or the creation of the Metropolitan Airport Authority, as the case may be. Each appointment shall be in writing and a certificate thereof signed by the appointing officer shall be filed and made a matter of record in the office of the county clerk wherein said organization proceedings are filed. A commissioner shall qualify within ten days after appointment by acceptance and the taking of the constitutional oath of office, both to be in writing and similarly filed for record in the office of the said county clerk. Members initially appointed to the board of commissioners of such Authority shall serve from date of appointment for one, two, three, four and five years and shall draw lots to determine the periods for which they each shall serve. In case there are more than five commissioners, lots shall be drawn so that five commissioners shall serve initial terms of one, two, three, four and five years and the other commissioners shall serve terms of one, two, three, four or five years as the number of commissioners shall require and the drawing of lots shall determine. Within 30 days after September 27, 1985, the chairman of a county board who is to appoint 5 commissioners at large pursuant to this amendatory Act of 1985 shall appoint 2 such commissioners to serve terms of 3 years and 5 years, respectively, as determined by lot. The other 3 commissioners to be appointed at large shall be appointed by such chairman to succeed the terms of the commissioners holding office on such date who were appointed at large or from the areas within the Authority located outside of municipalities having a population of 5,000 or more; provided that such commissioners then holding office shall continue to serve the terms for which they were appointed. The successors of all such initial members of the board of commissioners of an Authority shall serve for terms of five years, all such appointments and appointments to fill vacancies shall be made in like manner as in the case of the initial commissioners except as otherwise provided in this Section. A commissioner having been duly appointed shall continue to serve after the expiration of his term until his successor has been appointed. Each commissioner shall reside within the Authority and shall continue to reside therein during his term of office.
70 ILCS 5/3.4