Tennessee Code Title 35. Fiduciaries and Trust Estates § 35-3-106

Investments may be made in bonds and notes of any county, city or town in any state or territory of the United States that has a population, as shown by the last federal census next preceding the investment, of not less than forty-five thousand (45,000) and has not defaulted within twenty-five (25) years next preceding the investment, for more than thirty (30) days, in the payment of any part of either principal or interest of any bond, note or other evidence of indebtedness.