1820
The Missouri Compromise is reached after a bitter debate over the issue of slavery in a new state. Slavery is to be barred north of a latitude paralleling the southern border of Missouri.

1832
South Carolina attempts to nullify federal tariffs, defying the authority of Congress.

1850
After the application of California to join the Union, the Compromise of 1850 is reached in Congress. The legislation admits California as a free state; New Mexico and Utah are organized as territories with the residents of each to decide on slavery. A Fugitive Slave Act is passed in an attempt to hinder runaway slaves.

1852
Harriet Beecher Stowe's antislavery novel Uncle Tom's Cabin whips up abolitionist sentiment in the North.

1854
The Kansas-Nebraska Act permits the population of new territories to decide whether or not to permit slavery within their borders.

1857
March 6: In the Dred Scott decision, the Supreme Court denies the petition of a...