What tactics were used in the south to prevent african americans from voting after the passage of the 15th amendment and how did it affect the elections

The 15th amendment allowed African American men the right to vote.
The tactics were: making the Literacy Test (The test given to the people in order to vote) the literacy test was made to be hard and filled with crazy questions so most of the voters would get the questions wrong. (one answer you get wrong denotes failure to the test). It affected the elections because the people running to be President would get less voters- and possibly have a better chance of having more votes! 

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