Proposition 4 allows a county to issue bonds to pay for underdeveloped or blighted areas of a county.  Through repayment of these bonds, this amendment does not permit a county to increase ad valorem taxes.

Find more information here: http://www.lrl.state.tx.us/legis/billsearch/amendmentDetails.cfm?amendmentID=651&legSession=82-0&billTypedetail=HJR&billNumberDetail=63