The slave trade was banned in 1808, but the enslaved black population still grew to 4 million by 1860 through reproduction. By then, there were around 250,000 freed blacks mostly in the upper South. Freed blacks faced restrictions on where they could work and live. Abolitionists like Theodore Dwight Weld, William Lloyd Garrison, and David Walker published works condemning slavery and calling for emancipation, while the American Colonization Society unsuccessfully tried to transport blacks to Africa. Southerners defended slavery and said it benefited blacks, while abolitionist speeches in the North angered mobs.