History of slavery in the United States by state

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).

Source: Wikipedia — History of slavery in the United States by state (CC BY-SA 4.0)