| 1820 | |
| 1846 | - Wilmot Proviso introduced.
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| 1847 | - Wilmot Proviso defeated in Senate.
- “Popular sovereignty” compromise offered.
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| 1848 | - Free-Soil Party founded.
- Zachary Taylor elected president.
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| 1849 | |
| 1850 | - Taylor dies; Vice President Millard Fillmore becomes president.
- Compromise of 1850 becomes law.
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| 1852 | - Uncle Tom’s Cabin published.
- Franklin Pierce elected president.
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| 1853 | |
| 1854 | - American (Know-Nothing) Party emerges.
- Kansas-Nebraska Act.
- Republican Party founded.
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| 1856 | - “Bleeding Kansas.”
- “Sack of Lawrence.”
- Pottawatomie massacre.
- James Buchanan elected president.
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| 1857 | - Dred Scott decision.
- Congress rejects Lecompton constitution.
- Panic of 1857.
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| 1858 | - Lincoln-Douglas debates; Douglas wins Senate seat.
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| 1859 | - John Brown raids Harpers Ferry.
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| 1860 | - Abraham Lincoln elected president.
- South Carolina secedes from Union.
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| 1861 | - Six other Lower South states secede.
- Confederate States of America formed.
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