Fifteenth Amendment, Guaranteeing Right to Vote, is Ratified
The Fifteenth Amendment was the last of three amendments introduced in the wake of the Civil War (often referred to as the Reconstruction Amendments). The Thirteenth Amendment abolished slavery. The Fourteenth Amendment declared that “all persons born or naturalized in the United States . . . are citizens of the United States and of the State wherein they reside.” The Fifteenth Amendment, ratified on this day, 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.”
However, through the use of poll taxes, literacy tests and sheer intimidation and terrorist tactics, Southern states were able to effectively disenfranchise African-Americans. It would take the passage of the Voting Rights Act of 1965, signed by President Lyndon Johnson on August 6, 1965, before the majority of African-Americans in the South were registered to vote.
Read the Fifteenth Amendment: http://www.archives.gov/exhibits/charters/constitution_amendments_11-27.html
Learn about the history of the right to vote: Alexander Keyssar, The Right to Vote: the Contested History of Democracy in the United States (2000)