The Fifteenth Amendment to the United States Constitution was ratified on Feb. 3, 1870, guaranteeing voting rights to citizens regardless of race.
The 15th Amendment granted African American men the right to vote by declaring that the "right of citizens of the United States to vote shall not be denied or abridged by the United States or by any state on account of race, color, or previous condition of servitude."
(Women, of course, didn't get the right to vote until the Nineteenth Amendment was ratified on Aug. 18, 1920.)
Although ratified on Feb. 3, 1870, the promise of the 15th Amendment would not be fully realized for almost a century. Southern states were able to prevent African Americans from voting through the use of poll taxes, literacy tests and other means.
It would take the passage of the Voting Rights Act of 1965 which outlawed discriminatory voting practices before the majority of African Americans in the South were registered to vote.
President Lyndon B. Johnson signed the Act into law on Aug. 6, 1965 with Martin Luther King, Jr., Rosa Parks, and other civil rights leaders in attendance.