In the 400 years up to 1850, an estimated seven million Africans were shipped to North America and sold into bondage labor.
By 1790 the rising value of cotton had made the slave trade profitable in the United States. By 1860, four million people–15 percent of the nation’s population–lived in slavery. Some bought their way out of slavery while others escaped to freedom.
People in bondage had always escaped. By 1830, more were aided by growing free black communities, abolitionists in the United States, and the prohibition of slavery in Canada and the Caribbean. A network of escape became known as the Underground Railroad. Sustained by ideals of the Declaration of Independence that “all men are created equal,” and from the Bible “remembering those in bonds as bound with them,” people both black and white established freedom routes.