The answer is: African American voter registration rates were equal to white registration rates.
The Voting Rights Act of 1965 prohibited discrimination in the right to vote of African-Americans in the United States, because some states required literacy tests or the payment of some tax to vote, using these resources to limit the right to the vote of the black people.
As a consequence, in the following years, the register of African-American voters increased and it was equal to the white people.