Why was the Fifteenth Amendment unable to protect African Americans' voting rights?

The United States 15th Amendment made voting legal for African-American men. However, voting for them was almost nonexistent in some places, especially in the South, because of threats, violence, and unethical practices

i don't see how you want other people to do your work for you and it is like you are just handing your assignment to anybody else and having them deal with it instead of your self i thought this site was for asking questions and somebody could you on it not just handing your work to somebody else to deal with it just saying don't mean to be mean just proving a fact.

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