In all cases in which, before the effective date of this Act, the regional superintendent of schools of a multicounty educational service region containing all of the territory of an elementary school district and all of the territory of a high school district proposed to be established and organized into a community unit school district has called an election for the purpose of submitting to the electors the proposition of establishing and organizing such territory into a community unit school district, and when the elementary and high school districts proposed to be so established and organized into a community unit school district had coterminous boundaries and the election on the proposition to establish and organize the territory of such districts into a community unit school district was preceded by petition therefor and hearing thereon and approval of the petition by such regional superintendent and by the State Superintendent of Education, and when a majority of the electors voting on the proposition at an election held in November of 1987 has voted in favor of the proposition to establish and organize such territory into a community unit school district, such election and the proceedings with respect to the petition, hearing and approval of the petition prior to such election are hereby made legal and valid, and such territory is hereby declared legally and validly organized and established as a community unit school district.