After the Civil War, Republican lawmakers pushed through a series of amendments to the US Constitution abolishing involuntary servitude, establishing birthright citizenship, and protecting the voting rights of black men, including the newly freed. What black and white Republicans accomplished during the early years of Reconstruction amounted to nothing less than a “second founding,” in the words of the great historian Eric Foner, remaking the Constitution and, along with it, the very relationship between citizens and their government.

But accepting the unprecedented novelty of emancipation and Reconstruction in the 1860s at face value requires making two additional assumptions with far-reaching implications. The first is that slavery in the United States only ended during the Civil War; the second is that black men had been universally excluded from political participation from the nation’s founding.

Though seldom acknowledged, these assumptions hew closely to Chief Justice Roger B. Taney’s infamous Dred Scott decision of 1857, which effectively nullified the free status of black people throughout the country, regarded black chattel slavery as an unalterable fact based on the determinative category of race, and denied that any black person had ever been — or could ever be — a citizen. Free and enslaved African Americans may have influenced antislavery politics and the growing abolitionist movement but, the story goes, they did so as outsiders until abolition in 1865 and the advent of formal black citizenship at the national level in 1868.