In terms of the number of Constitutional Amendments devoted to it, slavery was undoubtedly the most divisive issue in American politics. Immediately following the end of the Civil War, before the Confederate states re-entered the Union, the thirteenth amendment formally abolished slavery, fulfilling Lincoln’s promise in the Emancipation Proclamation. The crucial part of the following amendment, ratified in 1868, gave citizenship to any person “born or naturalized in the United States,” effectively granting citizenship status for former slaves. Still, another amendment was needed before the freedmen would be given the right to vote.

On this day, March 30, in 1870, the fifteenth amendment to the constitution took effect, stating “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.”

Notably, this was not a granting of a right, but rather the prevention of its limit – Congress, in other words, took it as a given that the right to vote had always existed. Despite this ideological statement, for a century after blacks would be kept away from polls through combinations of intimidation tactics, literacy tests, taxes, and other semi-legal means.