Heather Cox Richardson is an American historian who teaches at Boston College. She writes an informative blog called “Letters from an American.” This one appeared recently.

She writes:

On July 9, 1868, Americans changed the U.S. Constitution for the fourteenth time, adapting our foundational document to construct a new nation without systematic Black enslavement.

In 1865, the Thirteenth Amendment to the Constitution had prohibited slavery on the basis of race, but it did not prevent the establishment of a system in which Black Americans continued to be unequal. Backed by President Andrew Johnson, who had taken over the presidency after an actor had murdered President Abraham Lincoln, white southern Democrats had done their best to push their Black neighbors back into subservience. So long as southern states had abolished enslavement, repudiated Confederate debts, and nullified the ordinances of secession, Johnson was happy to readmit them to full standing in the…