In the 15 years between 1865 and 1880, at least 13 states — more than a third of the country’s 38 states — enacted broad felony disenfranchisement laws. The theory was simple — convict them of crimes, strip away the right to vote, imprison them, and lease them out as convict labor and Blacks would be returned to a condition as close to slavery as possible.
No one tried to hide the intent of these laws.
In 1894, a white South Carolina newspaper argued that amendments to the voting laws were necessary to avoid whites being swept away at the polls by the Black vote. In 1901, Alabama amended its Constitution to expand disenfranchisement to all crimes involving “moral turpitude” — a vague term that was applied to felonies and misdemeanors. The president of that constitutional convention argued that manipulating the ballot to exclude Blacks was justified because of the need to avoid the “menace of Negro domination,” especially since Blacks were inferior to whites.
via The Racist Roots of Denying Incarcerated People Their Right to Vote | American Civil Liberties Union