Following the passage of the Fifteenth Amendment, states attempted to limit voting rights of African Americans through registration quotas.
state constitutions.
poll taxes and literacy tests.
blood tests and genealogy.

The states limit the rights poll taxes and literacy tests.

The Fifteenth Amendment of the United state constitution creates a additional provision to enable exercise of voting rights fo all citizens in the country, regardless of their race, color and skin.

In conclusion, the states limit their rights through collection of poll taxes and conduction of literacy tests, whereas such practice was unethical.

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The answer is poll taxes and literacy tests. These systematically placed African Americans at a disadvantage and was unethical.

Explanation:

because mexico wanted to choose a centralized location