Tenn. Code § 64-8-101
There is hereby established a regional transportation authority in the counties of Davidson, Sumner, Williamson, Wilson, Robertson, Cheatham, Maury, Dickson and Rutherford. In order for Davidson, Sumner, Williamson, Wilson, Robertson, Cheatham, Maury, Dickson or Rutherford County or any city, town or metropolitan government located within one (1) of these counties to participate in the regional transportation authority, the local government must pay its yearly local assessment to the authority within the time frame established by the authority. A county or city, town or metropolitan government may opt out of participation by means of a notice to the authority that it is ceasing payment of its yearly assessment or the failure of any local government to pay its yearly assessment, after notice and within a time frame as established by the authority, shall result in a presumption of the authority that the local government's wishes to opt out of participation in the authority. Such presumption may be overcome by the local governments payment of current and past due assessments within a time frame established by the authority. The regional transportation authority shall be a body corporate and politic, shall be governed and managed as provided for in this chapter and shall have the powers and duties provided for by this chapter and other applicable provisions of the law.
T.C.A. § 64-8-101