What voting restrictions were enacted to keep African-American males from voting?

After the Civil War, federal troops remained in the Southern states to ensure that those who had been slaves were treated equally and properly. This was the era of Reconstruction.  During this period the 15th Amendment was passed, giving prior slaves and all African-Americans the right to vote.  But once federal troops withdrew from the South, in 1877, the Southern states did everything they could to prevent black Americans from voting.

Not every state took precisely the same actions to accomplish this, but there were any number of successful ways of keeping black people from voting. One was the poll tax. This required one to pay a fee in order to have the right to vote.  Former slaves, who were struggling for their economic existence, did not have the wherewithal to pay a poll tax. Another method was the literacy test.  Since it had been against the law to teach slaves how to read and write, few, if any, could pass such a test, and even free black Americans often could not do so.  I believe another method was requiring a voter to own land, and this kept African-Americans from voting, too.  When none of these was effective, there were always threats and intimidation.  Black people were threatened with physical harm and the loss of their jobs.

The South was bound and determined to not allow African-Americans to vote, because this was an imposition by the North, because Southerners still considered them to be property, not human beings, and because there were enough black people in these states to greatly influence the outcome of an election, even, during Reconstruction, to the point of electing black candidates.  Once Reconstruction was over, these various voting restrictions, as well as many other Jim Crow laws, were the Southerners effort to maintain their "values" and way of life.