Ohio constitution
Article XII: finance and taxation
Section 11

No bonded indebtedness of the state, or any political
subdivisions thereof, shall be incurred or renewed
unless, in the legislation under which such indebtedness
is incurred or renewed, provision is made for
levying and collecting annually by taxation an amount
sufficient to pay the interest on said bonds, and to provide
a sinking fund for their final redemption at
maturity.