Tennessee Code Title 13. Public Planning and Housing § 13-7-405

(b)(1) The regional historic zoning commission has the authority to submit recommendations to any county or municipal legislative body within the area served by the regional historic zoning commission regarding the creation of historic districts and zones in accordance with the definition set forth in this part. Prior to establishing a historic district or zone, the county or municipal legislative body of the area in which the establishment of the zone or district is being considered shall refer any historic district or zone proposal to the regional historic zoning commission for its recommendations, and the regional historic zoning commission shall furnish the legislative body its recommendations on such proposal in writing. In addition, the recommendation of the regional historic zoning commission shall be referred to the regional planning commission which shall consider the district or zone and refer its recommendation regarding the proposed district or zone to the legislative body in writing.

(2) This subsection (b) shall not apply in any county having a metropolitan form of government and having a population of not less than four hundred thousand (400,000) nor more than five hundred thousand (500,000), according to the 1980 federal census or any subsequent federal census.