Literacy tests, grandfather clauses, and poll taxes were enacted by southern states to?

They were all a way of practically limiting the right to vote of the African Americans, while making sure that white population can vote.

The southern states could no longer legally limit voting rights of African-Americans, but they used these measures to practically achieve the same effect.

It is meant that like tapestry scientific theories often need to pull out since they are not relevant and often times the whole chain of theories may be pulled out.