(1) Regulation of borrowing and debt. The General Assembly shall enact general laws relating to the borrowing of money secured by a pledge of the faith and credit and the contracting of other debts by counties, cities and towns, special districts, and other units, authorities, and agencies of local government.

  (2) Authorized purposes; two-thirds limitation. The General Assembly shall have no power to authorize any county, city or town, special district, or other unit of local government to contract debts secured by a pledge of its faith and credit unless approved by a majority of the qualified voters of the unit who vote thereon, except for the following purposes:

  (a) to fund or refund a valid existing debt;

  (b) to supply an unforseen deficiency in the revenue;

  (c) to borrow in anticipation of the collection of taxes due and payable within the current fiscal year to an amount not exceeding 50 per cent of such taxes;

  (d) to suppress riots or insurrections;

  (e) to meet emergencies immediately threatening the public health or safety, as conclusively determined in writing by the Governor;

  (f) for purposes authorized by general laws uniformly applicable throughout the State, to the extent of two-thirds of the amount by which the unit's outstanding indebtedness shall have been reduced during the next preceding fiscal year.

  (3) Gift or loan of credit regulated. No county, city or town, special district, or other unit of local government shall give or lend its credit in aid of any person, association, or corporation, except for public purposes as authorized by general law, and unless approved by a majority of the qualified voters of the unit who vote thereon.

  (4) Certain debts barred. No county, city or town, or other unit of local government shall assume or pay any debt or the interest thereon contracted directly or indirectly in aid or support of rebellion or insurrection against the United States.

  (5) Definitions. A debt is incurred within the meaning of this Section when a county, city or town, special district, or other unit, authority, or agency of local government borrows money. A pledge of faith and credit within the meaning of this Section is a pledge of the taxing power. A loan of credit within the meaning of this Section occurs when a county, city or town, special district, or other unit, authority, or agency of local government exchanges its obligations with or in any way guarantees the debts of an individual, association, or private corporation.

  (6) Outstanding debt. Except as provided in subsection (4), nothing in this Section shall be construed to invalidate or impair the obligation of any bond, note, or other evidence of indebtedness outstanding or authorized for issue as of July 1, 1973.