Slavery is made illegal in the north west territory the U.S consituation states that congress may not ban the slave trade in 1808
A federal fugitive slave law is enacted providing for the return slaves who had escaped and crossed state lines.
Congress bans the importation of slaves from africa.
The Missouri compromise bans slavery north of the southern boundary of Missouri.
The slave population in u.s numbers more than two million, making the ratio of free 5.5:1
Texas enters the union as a slave state.
The slave population is now nearly four million, making the ratio of free to enslaved Americans approximately 7:1.
President Lincoln issues the emancipation, proclamation, declaring that "all persons held as slaves" within the confederate state "are and henceforward shall be free