2. One of the primary reasons for the reinvigoration of slavery was the invention and rapid widespread adoption of the cotton gin. This machine allowed Southern planters to grow a variety of cotton - short staple cotton - that was especially well suited to the climate of the Deep South.
3. The Missouri Compromise of 1820, which allowed Missouri to become a slave state, further provoked anti-slave sentiment in the North. The abolitionist movement began as a more organized, radical and immediate effort to end slavery than earlier campaigns. It officially emerged around 1830.