(70 ILCS 2105/15)
(from Ch. 42, par. 398)
At the time of or before incurring any indebtedness, the board of
trustees shall provide for the collection of a direct annual tax sufficient
to pay the interest on such debt as it falls due, and also to pay and
discharge the principal thereof as the same shall fall due, and at least
within twenty years from the time of contracting same.
(Source: Laws 1925, p. 346.)