The governing body of a locality may by ordinance or resolution, or the governing bodies of two or more localities may by concurrent ordinances or resolutions or by agreement, create a tourism financing development authority for the purpose of supporting tourism infrastructure in localities. The name of the authority shall contain the word “authority.” The authority shall be a public body politic and corporate. Any such locality that levies a transient occupancy tax pursuant to § 58.1-3819 shall designate any excess over two percent to be used for purposes of the authority except such revenues that are otherwise encumbered by the locality.