[T]he destiny of the Negroes is in some measure interwoven with that of the Europeans. These two races are fastened to each other without intermingling; and they are alike unable to separate entirely or to combine. The most formidable of all the ills that threaten the future of the Union arises from the presence of a black population upon its territory; and in contemplating the cause of the present embarrassments, or the future dangers of the United States, the observer is invariably led to this as a primary fact. —Alexis de Tocqueville
