How did literacy tests or poll taxes undermine the civil rights granted to African Americans by the 14th and 15th Amendments?

Literacy tests.

After the American Civil War ended in victory for the Union, the 14th and 15th Amendments were ratified and provided for African Americans to be able to vote. The Southern States passed a series of laws aimed at ensuring that African Americans could not vote including the Literacy tests.

These tests required that people voting needed to prove how literate they were. African Americans were disadvantaged by this however because they had not been offered education as enslaved people and even then the State did not educate them so they failed the literacy tests and were unable to vote.

Poll Taxes.

These required a certain payment to be able to vote. African Americans had been denied economic opportunities and so could not pay the poll Taxes and so could not vote. Most poor whites were exempted from this by the Grandfather clause which meant that they did not have to pay if their grandfathers had voted even once, something African Americans could not claim as they had just been recognised as citizens and had previously been unable to vote.