Yes, but that doesn’t mean unions cannot exist….it means union membership cannot be forced on anyone.
[Isn’t Tennessee a right to work state ?]
Yes, but “Right to Work” doesn’t ban unions it bans closed shops where employees are forced to pay union dues as a condition of employment. The GM/Saturn plant in Spring Hill is unionized. The difference between it and plants in some northern states is that employees do not have to join the union or pay dues.