Even though The Mississippi Plan was elaborated in 1875, it wasn't until 1890 when the state of Mississippi adopted a new constitution with which the black people were effectively disenfranchised.
In order to vote, the voters were required to pay a poll tax and pass a subjective literacy test which was applied by white administrators. These barriers weren't the only measures taken, since black people who tried to vote were victims of violence and fraud. This situation continued to happen until the black population stopped trying to exercise their rights.
Other southern states called it "The Mississippi Plan" and they quickly adopted it.