| One method of preventing African-Americans from voting after the Civil Rights Act was passed. Literacy tests were required at the registrar before someone could register to vote.
The tests were completely impossible and meant to legally exclude "undesirables" (which mainly meant Blacks) from voting. Poor whites were exempt from this by Grandfather Clause laws that allowed them to vote despite illiteracy because a member of their family had voted before the Civil War. This conveniently excluded African-Americans because, of course, none of them could vote before the Civil War.
This practice was made illegal by the Voting Rights Act. This act enabled the federal government to intervene if discriminatory tactics were used to mess with voting. | 
