From 1775 to 1830, many African Americans gained freedom from slavery, yet during the same period the institution of slavery expanded. How did both...

This apparently contradictory trend can be explained in a few ways. First, the American Revolution produced a brief period of emancipationist zeal that extended even to the upper South. Almost every northern state passed gradual emancipation laws that brought slavery to an end in the period covered by this question. Massachusetts even abolished slavery outright by court decision. Even in Virginia, many slaveholders, most famously George Washington, freed their slaves (Washington did so in his will). But the period also featured massive economic change that revitalized slavery in the Deep South and led to its expansion. The most important of these changes was the introduction of the cotton gin, which made short staple cotton, which could grow in the Southern upcountry, a viable crop. Fueled by the demand created by the Industrial Revolution in the Northeast, England, and France, would-be cotton planters invested millions in slaves, many of which were sold south from the Upper South, where the climate and soils was less conducive to cotton cultivation. So the number and value of slaves expanded dramatically after 1815 or so, and this trend continued until the outbreak of the Civil War. As for how African-Americans reacted to these changes, their responses varied. Some free blacks in the North participated in the abolitionist movement and sheltered fugitives from the South. Some slaves ran away, and a few, most famously Nat Turner, violently resisted their enslavement. But most simply tried, through everyday actions, to keep their families intact, preserve their humanity, and ameliorate their working conditions as best they could.