South Carolina
After the Civil War, African-Americans in South Carolina got to vote for some time, but soon black codes were enacted, and white-supremacist groups like the KKK were reborn, restricting African-Americans from voting. South Carolina thus became a Democratic stronghold. In fact, in 1904, Republican Theodore Roosevelt, who was running for president, won less than 5% of the vote in the state. The Democratic candidate won over 95% of the vote. This cult of fear disabled most African-Americans in South  Carolina from voting till 1965, when President Johnson signed the Voting Rights Act.