Tennessee Code Title 9. Public Finances § 9-3-103

Whenever any county, metropolitan government, incorporated town or city or special district of this state is authorized by law to enter into any loan agreement, indenture or other contract or instrument for the borrowing of money, such loan agreement, indenture or other contract or instrument may be for such term as the parties thereto may agree, but in no event may such term exceed forty (40) years or the term otherwise authorized by law, and may provide for such security as authorized by law for the term of such loan agreement, indenture or other contract or instrument.