35 ILCS 200/10-130

In counties with more than 3,000,000 inhabitants, the equalized assessed value per acre of farmland shall be the lesser of either 16% of the fair cash value of the farmland estimated at the price it would bring at a fair, voluntary sale for use by the buyer as a farm as defined in Section 1-60, or 90% of the 1983 average equalized assessed value per acre certified by the Department.