(105 ILCS 5/16-4) (from Ch. 122, par. 16-4)
    Sec. 16-4. Building jointly used - Sale of interest - Additions and enlargements. Whenever two school districts situated adjacent to one another or comprising the same or partly the same territory have a school site with buildings thereon, owned by one of the districts but used under agreement by both, the district owning the site and buildings may sell to the other, and the other district has the right to purchase, an equal or any other interest in the site and buildings under an agreement between the two; and upon the execution of the agreement and the acquiring the title to the interest by the purchasing district, the two districts shall be deemed to hold title to the premises as tenants in common; and thereafter the school districts, or either of them, may, under appropriate terms in the first agreement, or under a new agreement entered into by them, add to and enlarge any parts of the buildings, if deemed necessary for the uses of the districts or either of them, and by such sole or mutual expenditure of funds as may be nominated by the terms of the agreement between the districts, and the expenditures shall in no way change the individual interests of the districts in the premises unless otherwise expressly so provided by the terms of the agreement.
(Source: P.A. 81-1541.)