Following the creation of the United States in 1776 and the ratification of the U.S. Constitution in 1789, the legal status of slavery was generally a matter for individual U.S. state legislatures and judiciaries (outside of several historically significant exceptions including the Northwest Ordinance of 1787, the 1808 Act Prohibiting Importation of Slaves, the 1820 Missouri Compromise, the Fugitive Slave Act of 1850, the Dred Scott v. Sandford decision of 1857, et al.) As such, slavery flourished in some states (mostly southern), and withered on the vine in others (mostly northern). On the whole, the former Thirteen Colonies abolished slavery relatively slowly, with Northern states often using gradual emancipation systems in which freedom would be granted after so many years of life or service (Vermont and New York had clear and absolute freedom dates).
For many years after the establishment of the republic, new states were admitted in pairs, so-called free state–slave state twins, so that some states entered the Union with guaranteed "free soil" while their twin permitted the continuation and expansion of America's peculiar institution. Fifteen states (Delaware, Georgia, Maryland, South Carolina, Virginia, North Carolina, Kentucky, Tennessee, Louisiana, Mississippi, Alabama, Missouri, Arkansas, Florida, and Texas) never sought to end slavery, and thus bondage and the slave trade continued in those places, and there was even a movement to reopen the transatlantic slave trade. Ultimately, a massive and devastating four-year-long war resolved the interstate conflict over slavery, and when rebel state governments were finally overwhelmed by force of arms, various representatives of the U.S. federal government emancipated those people who remained legally enslaved. Slavery in the United States was abolished nationwide within the 36 newly reunited states under the Thirteenth Amendment to the United States Constitution, effective December 18, 1865.
The federal district, which is legally part of no state and under the sole jurisdiction of the U.S. Congress, permitted slavery until the American Civil War. For the history of the abolition of the slave trade in the district and the federal government's one and only compensated emancipation program, see slavery in the District of Columbia.
Slavery in states admitted after 1865
History of slavery in Alaska
History of slavery in Colorado
History of slavery in Montana
History of slavery in Nebraska
History of slavery in New Mexico
History of slavery in Oklahoma
History of slavery in South Dakota
History of slavery in Utah
See also
Border states (American Civil War)