The 15th Amendment, granting African-American men the right to vote , was formally adopted into the U.S. Constitution on March 30, 1870 after the House of Representatives passed the 15th Amendment on February 25, 1869, by a vote of 144 to 44, and the Senate passed the 15th Amendment on February 26, 1869 , by a vote of 39 to 13. Passed by Congress the year before, the amendment reads: “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.”

President Ulysses S. Grant called the amendment “the most important event that has occurred since the nation came into life,” Grant urged whites not to interfere with the enforcement of the new provision, and reminded African Americans of their responsibilities as voters. News of the Fifteenth…