In what ways did the emergence of the anti-slavery movement impact American society and politics?

The anti-slavery movement started as something only a minority of Americans wanted.  There were always fears of what would happen if the slaves were freed, and many Americans, while not personally in favor of slavery, were afraid of a slave revolt.  The anti-slavery movement had religious undertones as well, as many claimed that if all were equal in the eyes of God, then slavery was a moral evil.  William Lloyd Garrison's newspaper The Liberator was...

The anti-slavery movement started as something only a minority of Americans wanted.  There were always fears of what would happen if the slaves were freed, and many Americans, while not personally in favor of slavery, were afraid of a slave revolt.  The anti-slavery movement had religious undertones as well, as many claimed that if all were equal in the eyes of God, then slavery was a moral evil.  William Lloyd Garrison's newspaper The Liberator was one of the great early anti-slavery publications, and Garrison achieved fame and notoriety when he burned a copy of the Constitution because he said that he could not support a document that assisted slavery.  Slavery became such an issue in Congress that Congress passed a "gag rule," which meant that they would not talk about it.  When the United States expanded, there were worries that the balance between free and slave states would be disrupted, so Congress passed the Compromise of 1820. This created a line at the southern border of Missouri, although Missouri was a slave state, and allowed the creation of Maine as a free state.  In 1840, James Birney ran as an abolitionist candidate in response to Whigs who could not accept slavery.  Slavery was the key issue in the Compromise of 1850 as the nation sought to add new territory but not disrupt the delicate balance between free and slave states.  In 1856, the Republican Party ran on a platform of not allowing slavery into the new territories.  Slavery was also at the heart of an American bestseller; Uncle Tom's Cabin provided a dramatic portrayal of what life was like for a slave family.  The book inflamed passions in both free and slave states—more Northerners called slavery barbaric and more Southerners called the book a farce because Stowe did not study slavery closely.