The Abolitionist Movement
By 1804, all northern states had abolished slavery, and Congress outlawed African slave trade in 1808. However, domestic slave trade continued to flourish, and the population of enslaved Africans had reached nearly 4 million by 1860. Free blacks and northern abolitionists began helping fugitive slaves escape from the South through the Underground Railroad (a network of safe houses) in the 1780s. Up to 100,000 slaves escaped to freedom on the Underground Railroad, and this success both spread abolitionist feelings and increased sectional tensions. The abolitionist movement gained popularity in the north between the 1830s and 1860s. Some abolitionists based their actions on the belief that slavery was a sin, while others argued that “free-labor” was regressive, inefficient, and made little economic sense.