| 1830 | - The Book of Mormon published.
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| 1836 | - Battle of the Alamo.
- Texas declares independence from Mexico.
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| 1837 | |
| 1840s | - Practical mechanical reapers created.
- Fourierist communities founded.
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| 1841 | - First wagon trains head west on Oregon Trail.
- Vice President John Tyler becomes president when William Henry Harrison dies.
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| 1844 | - James K. Polk elected president.
- Samuel F. B. Morse demonstrates telegraph.
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| 1845 | - Term manifest destiny coined.
- Texas enters Union as slave state.
- Potato blight spurs Irish immigration.
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| 1846 | - Bear Flag Revolt.
- Congress declares war on Mexico.
- United States and Great Britain divide Oregon Country.
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| 1847 | |
| 1848 | - Treaty of Guadalupe Hidalgo.
- Oneida community organized.
- Seneca Falls convention.
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| 1849 | - California gold rush begins.
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| 1850 | - Utah Territory annexed.
- Railroads granted six square miles of land for every mile of track.
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| 1851 | - Fort Laramie conference marks the beginning of Indian concentration.
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| 1855 | - Massachusetts integrates public schools.
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| 1857 | |
| 1861 | - California connected to nation by telegraph.
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