Toward the end of the Reconstruction era, something very significant happened. That is what was known as the Populist Movement. The leaders of this movement began awakening the poor white masses and the former Negro slaves to the fact that they were being fleeced by the emerging Bourbon interests. Not only that, but they began uniting the Negro and white masses into a voting bloc that threatened to drive the Bourbon interests from the command posts of political power in the South.
To meet this threat, the southern aristocracy began immediately to engineer this development of a segregated society. I want you to follow me through here because this is very important to see the roots of racism and the denial of the right to vote. Through their control of mass media, they revised the doctrine of white supremacy. They saturated the thinking of the poor white masses with it, thus clouding their minds to the real issue involved in the Populist Movement. They then directed the placement on the books of the South of laws that made it a crime for Negroes and whites to come together as equals at any level. And that did it. That crippled and eventually destroyed the Populist Movement of the nineteenth century.
— MLK, Address at the Conclusion of the Selma to Montgomery March