Attempts to maintain the Union, c1845–1854
1. Westward expansion and its impact on North and South
2. Attempts at political compromise
3. The growth of abolitionist sentiment in the North
4. Reactions against abolitionism in the South
5. The outbreak of Civil War, 1854–1861
7. The emergence of the Republican Party
8. Hardening of positions
9. The drive for secession of the South