The antislavery movement paved the way for slavery's demise in America. It evolved through reform groups – religious and secular, white and black, during the colonial and Revolutionary eras, as “all men are created equal” became a national creed.

Circa 1780–1846, when every state north of Maryland gradually abolished bondage, many ex-slaves, Quakers, and some evangelical bodies opposed the American Colonization Society's program to emancipate slaves and relocate them to Africa. Black churches, which organized separate Baptist, Methodist, and other denominations, formed the vanguard of anticolonization and freedom struggles. They supported newspapers such as Freedom's Journal; maintained Vigilance Committees to assist runaway slaves; and presented petitions to Congress seeking termination of foreign and domestic slave trading. Prior to and after the suppression of slave conspiracies and revolts in Richmond, Virginia (1800); Charleston, South Carolina (1822); and Southampton, Virginia (1831), black and white churches and women's associations helped preserve the Underground Railroad.

Their activism vitalized interracial abolitionism, prodded southern secession, and grounded the Civil War. Frederick Douglass and Sojourner Truth joined white activists such as William Lloyd Garrison and Lydia Maria Child in the American Anti-Slavery Society, whose local chapters had small memberships. Chapters were forthright but not monolithic. Differences in their ideologies and strategies, for instance, peaceful protest versus electoral politics, divided Garrisonians and political abolitionists by 1840, when the latter group formed the Liberty Party. The party enlisted a coalition of moderates, militants, and radicals such as John Brown, who believed armed revolution was necessary for abolition. The war brought it, ending the “Peculiar Institution” and causing a “new birth of freedom.”