The U.S Constitution states that Congress may not ban the slave trade until 1808.
A federal fugitive slave law is enacted, providing for the return slaves who had escaped and crossed state lines.
Eli Whitney's invention of the cotton gin greatly increases the demand for slave labor.
Gabriel Prosser, an enslaved African American blacksmith, organizes a slave revolt intending to march on Richmond, Virginia. The conspiracy is uncovered, and Prosser and a number of the rebels are hanged. Virginia's slave laws are consequently tightened.
The Missouri Compromise bans slavery north of the southern boundary of Missouri.
Denmark Vesey, an enslaved African American carpenter who had purchased his freedom, plans a slave revolt with the intent to lay siege on Charleston, South Carolina. The plot is discovered, and Vesey and 34 coconspirators are hanged.
Nat Turner, an enslaved African American preacher, leads the most significant slave uprising in American history. He and his band of followers launch a short, bloody, rebellion in Southampton County, Virginia. The militia quells the rebellion, and Turner is eventually hanged. As a consequence, Virginia institutes much stricter slave laws.
The Wilmot Proviso, introduced by Democratic representative David Wilmot of Pennsylvania, attempts to ban slavery in territory gained in the Mexican War. The proviso is blocked by Southerners, but continues to enflame the debate over slavery.
Harriet Tubman escapes from slavery and becomes one of the most effective and celebrated leaders of the Underground Railroad.
The continuing debate whether territory gained in the Mexican War should be open to slavery is decided in the Compromise of 1850: California is admitted as a free state, Utah and New Mexico territories are left to be decided by popular sovereignty, and the slave trade in Washington, DC is prohibited. It also establishes a much stricter fugitive slave law than the original, passed in 1793.
Harriet Beecher Stowe's novel, Uncle Tom's Cabin is published. It becomes one of the most influential works to stir anti-slavery sentiments.
The Dred Scott case holds that Congress does not have the right to ban slavery in states and, furthermore, that slaves are not citizens.
John Brown and 21 followers capture the federal arsenal at Harpers Ferry, Va. (now W. Va.), in an attempt to launch a slave revolt.
The Confederacy is founded when the deep South secedes, and the Civil War begins.
President Lincoln issues the Emancipation Proclamation, declaring "that all persons held as slaves" within the Confederate state "are, and henceforward shall be free."
The Civil War ends. Lincoln is assassinated. The Thirteenth Amendment abolishes slavery throughout the United States. On June 19 slavery in the United States effectively ended when 250,000 slaves in Texas finally received the news that the Civil War had ended two months earlier.