Following its ratification by the necessary three-quarters of U.S. states, the 14th Amendment, granting citizenship to all persons born or naturalized in the United States—including formerly enslaved people—is officially adopted into the U.S. Constitution. Secretary of State William Seward issues a proclamation certifying the amendment.

Two years after the Civil War, the Reconstruction Acts of 1867 divided the South into five military districts, where new state governments, based on universal manhood suffrage, were to be established. Thus began the period known as Radical Reconstruction, which saw the 14th Amendment, which had been passed by Congress in 1866, ratified in July 1868. The amendment resolved pre-Civil War questions of African American citizenship by stating that “all persons born or naturalized in the United States…are citizens of the United States and of the state in which they reside.” The amendment then reaffirmed the privileges and rights of all citizens, and granted all these citizens the “equal protection of the laws.”

In the decades after its adoption, the equal protection clause was cited by a number of African American activists who argued that racial segregation denied them the equal protection of law. However, in 1896, the U.S. Supreme Court ruled in Plessy v. Ferguson that states could constitutionally provide segregated facilities for African Americans, so long as they were equal to those afforded white persons. The Plessy v. Ferguson decision, which announced federal toleration of the so-called “separate but equal” doctrine, was eventually used to justify segregating all public facilities, including railroad cars, restaurants, hospitals and schools. However, “colored” facilities were never equal to their white counterparts, and African Americans suffered through decades of debilitating discrimination in the South and elsewhere. In 1954, Plessy v. Ferguson was finally struck down by the Supreme Court in its ruling in Brown v. Board of Education of Topeka.

READ MORE: When Did African Americans Get the Right to Vote?