<Li> July 13: The Continental Congress under the Articles of Confederation passes the Northwest Ordinance to govern territory north of the Ohio River and west of Pennsylvania . The territory will become the states of Illinois, Indiana, Michigan, Ohio, Wisconsin and Minnesota . In the ordinance, Congress prohibits slavery and involuntary servitude in the territory and requires the return of fugitive slaves found in the territory to their owners . The law no longer applies as soon as the territories become states . Anti-slavery Northerners cite the ordinance many times over the years as precedent for the limitation, if not the abolition, of slavery in the United States . Despite the terms of the ordinance, Southern - born settlers will try and fail to pass laws to allow slavery in Indiana and Illinois . </Li> <Table> <Tr> <Td> 1787 </Td> <Td> <Ul> <Li> The new Constitution of the United States has compromises to protect slavery . Representation in the House and Electoral College is increased by counting each slave as three - fifths of a person (Article I, Section 2), the passage of any law that would prohibit the importation of slaves is forbidden for 20 years (Article I, Section 9) and the return of slaves who escape to free states is required (Article IV, Section 2). </Li> </Ul> </Td> </Tr> <Tr> <Td> 1789 </Td> <Td> <Ul> <Li> August 7: Congress re-adopts the Northwest Ordinance under the Constitution . </Li> </Ul> </Td> </Tr> <Tr> <Td> 1790 </Td> <Td> <Ul> <Li> U.S. slave population in the 1790 United States Census: 697,681 . The number will grow to 3,954,174 in 1860, 3.5 million of whom live in the seceding Southern states . </Li> </Ul> </Td> </Tr> <Tr> <Td> 1791 </Td> <Td> <Ul> <Li> Vermont admitted as a free state . </Li> <Li> Kentucky admitted by joint resolution of Congress before the State has adopted a constitution . </Li> <Li> Robert Carter III of Virginia begins gradually to free his 452 slaves . He will perform the largest manumission of slaves in U.S. history . </Li> </Ul> </Td> </Tr> <Tr> <Td> 1792 </Td> <Td> <Ul> <Li> Kentucky draws up a constitution as a slave state and is admitted to the union . </Li> </Ul> </Td> </Tr> <Tr> <Td> 1793 </Td> <Td> <Ul> <Li> Congress passes the Fugitive Slave Act of 1793 based on Article IV, Section 2 of the Constitution . </Li> <Li> Eli Whitney, Jr. invents the cotton gin, making possible the profitable large - scale production of short - staple cotton in the South . The demand for slave labor increases with the increase in profitable cotton production . </Li> </Ul> </Td> </Tr> <Tr> <Td> 1794 </Td> <Td> <Ul> <Li> By 1794 every state had banned the international slave trade, although South Carolina reopened it in 1803 . </Li> <Li> Congress in 1794 prohibits ships from engaging in the slave trade . </Li> </Ul> </Td> </Tr> <Tr> <Td> 1796 </Td> <Td> <Ul> <Li> Tennessee is admitted as a slave state . </Li> </Ul> </Td> </Tr> <Tr> <Td> 1798 </Td> <Td> <Ul> <Li> The legislatures of Kentucky and Virginia pass the Kentucky and Virginia Resolutions, which are anonymously written by Thomas Jefferson and James Madison . Most other states reject the Resolutions, which claim that the states can negate federal laws that go beyond the federal government's limited powers . In the second Kentucky resolution of November 1799, the Kentucky legislature says the remedy for an unconstitutional act is "nullification". </Li> </Ul> </Td> </Tr> <Tr> <Td> 1799 </Td> <Td> <Ul> <Li> New York enacts a law gradually abolishing slavery . </Li> <Li> George Washington dies on December 14, 1799 . His will frees the 124 slaves that he owns outright upon the death of his wife, Martha . They are freed by Martha in 1801, about 18 months before her death . </Li> <Li> Richard Allen, a black minister, calls on the nation's white leaders to follow Washington's lead . </Li> </Ul> </Td> </Tr> <Tr> <Td> 1800 </Td> <Td> <Ul> <Li> U.S. slave population in the 1800 United States Census: 893,605 (as corrected by late additions from Maryland and Tennessee). </Li> <Li> The Gabriel Plot was led by Gabriel Prosser, a literate blacksmith slave . He planned to take the Richmond, Virginia armory, then take control of the city, which would lead to freedom for himself and other slaves in the area . The plot is discovered before it is activated; Gabriel, along with 26 to 40 others, is executed . </Li> </Ul> </Td> </Tr> <Tr> <Td> 1803 </Td> <Td> <Ul> <Li> The United States purchases the Louisiana Territory from France . Slavery already exists and efforts to restrict it fail; the new lands permit a great expansion of slave plantations . </Li> <Li> Ohio, a free state, is admitted to the union . Three hundred Blacks live there and the legislature tries to keep others out . </Li> </Ul> </Td> </Tr> <Tr> <Td> 1804 </Td> <Td> <Ul> <Li> New Jersey enacts a law that provides for gradual abolition of slavery . All states north of the "Mason--Dixon line" (the boundary between Maryland and Pennsylvania) have now abolished or provided for the gradual abolition of slavery within their boundaries . </Li> <Li> The American Convention of Abolition Societies meets without any societies from Southern states in attendance . </Li> </Ul> </Td> </Tr> <Tr> <Td> 1805 </Td> <Td> <Ul> <Li> In January 1805, at Chatham Manor, near Fredericksburg, Virginia, slaves overpowered and whipped their overseer and assistants in protest of shortened holidays . An armed posse of white men quickly gathered to capture the slaves, killing one slave in the attack . Two others died trying to escape and the posse deported two others, likely to slavery in the Caribbean . </Li> </Ul> </Td> </Tr> <Tr> <Td> 1806 </Td> <Td> <Ul> <Li> Virginia repeals much of the 1782 law that permitted more liberal emancipation of slaves, making emancipation much more difficult and expensive . Also, a wife can revoke a manumission provision in her husband's will within one year of his death . </Li> </Ul> </Td> </Tr> <Tr> <Td> 1807 </Td> <Td> <Ul> <Li> With the expiration of the 20 - year ban on Congressional action on the subject, President Thomas Jefferson, a lifelong enemy of the slave trade, calls on Congress to criminalize the international slave trade, calling it "violations of human rights which have been so long continued on the unoffending inhabitants of Africa, and which the morality, the reputation, and the best interests of our country have long been eager to proscribe". </Li> <Li> At the urging of President Jefferson, Congress outlaws the international slave trade in an Act Prohibiting Importation of Slaves . Importing or exporting slaves becomes a federal crime, effective January 1, 1808; in 1820 it is made the crime of piracy . The trade had been about 14,000 a year; illegal smuggling begins and brings in about 1,000 new foreign - born slaves per year . </Li> <Li> John Randolph of Roanoke warns during the debates that outlawing the slave trade might become the "pretext of universal emancipation" and further warns that it would "blow up the constitution". If there ever should be disunion, he prophesies, the line would be drawn between the states that did and those that did not hold slaves . </Li> </Ul> </Td> </Tr> <Tr> <Td> 1810 </Td> <Td> <Ul> <Li> 1810 Census Data Volume 1 is unavailable online but a secondary source indicates that in 1810 there were 27,510 slaves in the North and 1,191,364 in the South . </Li> <Li> The percentage of free blacks increases in the Upper South from less than one percent before the Revolution to 10 percent by 1810 . Three - quarters of all blacks in Delaware are free . </Li> </Ul> </Td> </Tr> </Table> <Tr> <Td> 1787 </Td> <Td> <Ul> <Li> The new Constitution of the United States has compromises to protect slavery . Representation in the House and Electoral College is increased by counting each slave as three - fifths of a person (Article I, Section 2), the passage of any law that would prohibit the importation of slaves is forbidden for 20 years (Article I, Section 9) and the return of slaves who escape to free states is required (Article IV, Section 2). </Li> </Ul> </Td> </Tr> <Ul> <Li> The new Constitution of the United States has compromises to protect slavery . Representation in the House and Electoral College is increased by counting each slave as three - fifths of a person (Article I, Section 2), the passage of any law that would prohibit the importation of slaves is forbidden for 20 years (Article I, Section 9) and the return of slaves who escape to free states is required (Article IV, Section 2). </Li> </Ul>

13 events that led to the civil war