105 ILCS 5/17-2.1

The school board in any district having a population of less than 500,000 inhabitants may, by proper resolution, cause a proposition to authorize an annual tax, as prescribed in Section 17-2, for summer school educational purposes to be submitted to the voters of such district at a regular scheduled election. If a majority of the votes cast on the proposition is in favor thereof, the school board may thereafter levy the tax as authorized.