Tenn. Const. art. II, § 29

The General Assembly shall have power to authorize the several Counties and incorporated towns in this State, to impose taxes for County and Corporation purposes respectively, in such manner as shall be prescribed by law; and all property shall be taxed according to its value, upon the principles established in regard to state taxation. But the credit of no County, City or Town shall be given or loaned to or in aid of any person, company, association or corporation, except upon an election to be first held by the qualified voters of such county, city or town, and the assent of three-fourths of the votes cast at said election. Nor shall any county, city or town become a stockholder with others in any company, association or corporation except upon a like election, and the assent of a like majority. But the counties of Grainger, Hawkins, Hancock, Union, Campbell, Scott, Morgan, Grundy, Sumner, Smith, Fentress, Van Buren, and the new county herein authorized to be established out of fractions of Sumner, Macon and Smith Counties, White, Putnam, Overton, Jackson, Cumberland, Anderson, Henderson, Wayne, Cocke, Coffee, Macon, Marshall, and Roane shall be excepted out of the provisions of this Section so far that the assent of a majority of the qualified voters of either of said counties voting on the question shall be sufficient when the credit of such county is given or loaned to any person, association or corporation; Provided, that the exception of the counties above named shall not be in force beyond the year one thousand eight hundred and eighty; and after that period they shall be subject to the three-fourths majority applicable to the other counties of the State.