1777: Constitution of the Vermont Republic bans slavery.
1780: Pennsylvania passes An Act for the Gradual Abolition of Slavery, freeing future children of slaves. Those born prior to the Act remain enslaved for life. The Act becomes a model for other Northern states. Last slaves freed 1847.
1783: Massachusetts Supreme Judicial Court rules slavery illegal based on 1780 state constitution. All slaves are immediately freed.
1783: New Hampshire begins a gradual abolition of slavery.
1784: Connecticut begins a gradual abolition of slavery, freeing future children of slaves, and later all slaves
1784: Rhode Island begins a gradual abolition of slavery.
1787: The United States in Congress Assembled passed the Northwest Ordinance of 1787 outlawing any new slavery in the Northwest Territories.
1799: New York State passes gradual emancipation act freeing future children of slaves, and all slaves in 1827.
1802: Ohio writes a state constitution that abolishes slavery.
1804: New Jersey begins a gradual abolition of slavery, freeing future children of slaves. Those born prior to the Act remain enslaved for life.
1805: Great Britain: bill for Abolition passed in Commons, rejected in the House of Lords.
1806: U.S. President Thomas Jefferson in a message to Congress calls for criminalizing the international slave trade, asking Congress to "withdraw the citizens of the United States from all further participation in those violations of human rights … which the morality, the reputation, and the best of our country have long been eager to proscribe."
1807, 2 March: Jefferson signs the Act Prohibiting Importation of Slaves into law in the U.S. which took effect 1 January 1808.
1807: In the U.S. Northwest Territory (present-day Michigan),
1808: In the United States, Act Prohibiting Importation of Slaves takes effect 1 Jan.