All of Mississippi has a regulated grid, full of electric cooperatives which act as purchasing agents for their customers. There is no customer choice. In fact, all of Mississippi consists of electric cooperatives.
Mississippi is supplied by TVA, Entergy, and Mississippi Power – but additional power is wheeled in through additional coop purchasing, excluding the TVA.
The non-TVA region consists of Mississippi Power, Entergy, and Cooperative Energy (a coop aggregator). The result is that electric policy is completely different in TVA + non-TVA areas of the grid.