Short answers, pulled from the story.
Slavery in the United States was practiced from 1526 during the early colonial period and persisted in the country from its founding in 1776 until the Thirteenth Amendment was ratified on the 6th of December, 1865. At its peak just before the Civil War, the enslaved population in the South had reached four million people.
The Three-Fifths Compromise, negotiated by James Madison of Virginia, was written into Section 2 of Article I of the Constitution. It counted enslaved people as three-fifths of a person for the purposes of apportioning congressional representation and federal taxation, inflating the political power of slaveholding states in Congress and the Electoral College without granting enslaved people any rights.
After Congress banned importation of enslaved people in 1808, the domestic slave trade became a massive internal forced migration. Between 1830 and 1840, nearly 250,000 enslaved people were taken across state lines, and historians estimate close to one million were moved in total. Historian Ira Berlin called this the "Second Middle Passage." Slave traders transported two-thirds of those who moved west.
Nat Turner's Rebellion occurred in 1831 in Southampton County, Virginia. Turner, a literate enslaved man who claimed spiritual visions, led a group that killed nearly sixty white inhabitants before being subdued by the militia. Turner and seventeen other rebels were hanged. In retaliation, militias killed more than one hundred enslaved people who had not participated in the uprising.
The Fugitive Slave Clause, found in Article IV of the Constitution, prohibited any state from freeing an enslaved person who had fled there from another state and required that such people be returned to those claiming ownership. The Fugitive Slave Act of 1793 and the Fugitive Slave Act of 1850 gave the clause legal effect in federal law.
Senator John C. Calhoun declared slavery "a positive good" in a famous 1837 Senate speech, arguing that every civilized society required a laboring underclass. Writers James Henry Hammond and George Fitzhugh built on this view, with Hammond presenting his "Mudsill Theory" in a Senate speech on the 4th of March, 1858. Confederate Vice President Alexander Stephens articulated the ideology's logical end in his Cornerstone Speech on the 21st of March, 1861, declaring the Confederacy was founded on the premise that Black people were not equal to white people.