Unit 6 covers the decades between the War of 1812 and the Civil War, when the United States grew richer, bigger, and more religiously energized, and also more divided over slavery. After this unit you should be able to explain how economic change, westward expansion, and reform movements contributed to sectional conflict and Southern secession in 1860-1861.
Read the overview first for the big picture, then work through each topic's notes and answer the checkpoint question before moving on.
Antebellum means "before the war," and the label usually covers about 1815 to 1861. This unit tracks four changes that happened at the same time and fed each other. Keeping all four in view helps you explain why the Civil War came when it did.
Honors US History Unit 6 covers antebellum America, roughly 1815-1861. You study the market revolution (canals, railroads, factories, and the cotton boom), territorial expansion and Manifest Destiny (Indian removal, Texas, Oregon, and the Mexican-American War), the growth of slavery and the abolitionist movement along with the political crises of the 1850s, and the Second Great Awakening and the reform movements it inspired, such as temperance, public schools, and women's rights. The unit ends with Lincoln's election in 1860 and the first wave of Southern secession before the Civil War began.
Northern mills ran on Southern cotton, and Southern planters relied on Northern banks and shippers. But the North built a free-labor economy of wage workers, cities, and immigrants, while the South doubled down on plantation agriculture and enslaved labor. Shared trade did not produce shared values.
The Louisiana Purchase led to the Missouri crisis of 1819-1820. The Wilmot Proviso proposed banning slavery in land acquired from Mexico in 1846, and the Mexican Cession led to the Compromise of 1850. Many Americans supported expansion, but others opposed it, and the question of slavery in new territories divided national politics.
Many preachers in the Second Great Awakening taught that individuals could choose salvation, and some reformers believed society could be perfected. Reformers applied their beliefs to issues such as drinking, schools, prisons, women's rights, and slavery. Once slavery became a question of sin for many Northerners, splitting the difference became much harder.
Economic growth, territorial growth, and the growth of reform movements all made the nation stronger in some ways. Each one also sharpened the divide between a free-labor North and a slaveholding South. By 1860, Southern leaders believed a Republican president who opposed slavery's expansion threatened slavery itself, and they chose secession.
Between about 1815 and 1860, the US shifted from a mostly farm-and-workshop economy to a national market economy.
Between 1803 and 1853, the US more than tripled in size.
The enslaved population grew from about 700,000 in 1790 to nearly 4 million in 1860.
The Second Great Awakening was a wave of Protestant revivals from about the 1790s to the 1840s.
Open this guide for a closer review of the topic.
Between about 1815 and 1860, the US shifted from a mostly farm-and-workshop economy to a national market economy. Historians call this the market revolution. Instead of making most of what they used, families increasingly produced goods to sell and bought what they needed.
Transportation drove the change. The Erie Canal (finished 1825) linked the Great Lakes to New York City and cut the cost of shipping freight from Buffalo by roughly 90 percent. By 1860 the country had about 30,000 miles of railroad track, most of it in the North.
Factories followed. In Lowell, Massachusetts, water-powered textile mills hired young farm women and ran on strict schedules. Interchangeable parts, often credited to Eli Whitney but developed largely at federal armories like Springfield, made mass production possible. After the Irish potato famine began in 1845, Irish immigrants filled many factory, canal, and railroad jobs, and many German immigrants settled in Midwestern farms and cities.
The South grew too, but differently. Whitney's cotton gin (1793) made short-staple cotton profitable across the Deep South, and by 1860 cotton made up more than half of US exports by value. Northern and British mills depended on cotton picked by enslaved people, so the regional economies stayed linked even as their societies diverged.
The cotton gin was a labor-saving machine, so why did slavery grow after it was invented? It saved labor in cleaning cotton. As cleaning became cheaper, planters expanded cotton production onto new land and forced more enslaved people to plant and pick it.
Between 1803 and 1853, the US more than tripled in size. The Louisiana Purchase (1803) bought about 828,000 square miles from France for $15 million, and the Adams-Onís Treaty (1819) gained Florida from Spain.
Expansion came at the direct expense of Native nations. Andrew Jackson signed the Indian Removal Act in 1830. In Worcester v. Georgia (1832), the Supreme Court ruled that Georgia's laws had no force in Cherokee territory. Georgia released the imprisoned missionaries involved in the case in 1833, but the ruling did not stop removal. In 1838-1839 federal troops forced the Cherokee west on the Trail of Tears, and about 4,000 of roughly 16,000 died.
In 1845 journalist John L. O'Sullivan coined "Manifest Destiny," the belief that God intended Americans to spread across the continent. It was an ideology, not a law, and it carried racial assumptions that white Americans deserved land held by Native peoples and Mexicans.
Texas, independent from Mexico since 1836, was annexed in 1845. President Polk then settled Oregon with Britain at the 49th parallel (1846) and sent troops into land between the Nueces River and the Rio Grande that Mexico claimed. The Mexican-American War (1846-1848) ended with the Treaty of Guadalupe Hidalgo, which gave the US about 525,000 square miles for $15 million. Gold was discovered in California that same year, and the fight over slavery in this new land started almost immediately.
Why did Congress wait nine years to annex Texas after it won independence in 1836? Texas would enter as a slave state, and many Northerners opposed upsetting the balance between free and slave states. Annexation also risked war with Mexico.
| Acquisition | Year | How it was gained | Slavery question it raised |
|---|---|---|---|
| Louisiana Purchase | 1803 | Bought from France for $15 million | Missouri's request to enter as a slave state led to the Missouri Compromise of 1820 |
| Texas | 1845 | Annexed by joint resolution of Congress | Added a large slave state and helped trigger war with Mexico |
| Oregon Country | 1846 | Treaty with Britain at the 49th parallel | Little conflict, since few expected slavery to take root there |
| Mexican Cession | 1848 | Taken in the Mexican-American War, with $15 million paid to Mexico | Wilmot Proviso fight and the Compromise of 1850 |
| Gadsden Purchase | 1853 | Bought from Mexico for $10 million | Meant to secure a southern railroad route, which Northerners saw as favoring the South |
The enslaved population grew from about 700,000 in 1790 to nearly 4 million in 1860. Roughly one million people were sold from the Upper South to the cotton states of the Deep South, often separated from their families. Only about a quarter of white Southern families enslaved anyone in 1860, but planters held most of the region's political power.
Enslaved people resisted through slowdowns, escape, and sometimes revolt. After Nat Turner's 1831 rebellion in Virginia killed about 55 white people, Southern states tightened slave codes, including bans on teaching enslaved people to read.
Abolitionism grew in the 1830s. William Lloyd Garrison began The Liberator in 1831 and demanded immediate emancipation. Frederick Douglass published his Narrative in 1845, and Harriet Tubman led about 70 people to freedom on the Underground Railroad. Abolitionists were still a minority, though. Many more Northerners backed free soil, which opposed slavery's spread into the West without demanding its end in the South.
The 1850s became a chain of failed fixes. The Compromise of 1850 included a harsh Fugitive Slave Act, and Uncle Tom's Cabin (1852) spread outrage. The Kansas-Nebraska Act (1854) led to Bleeding Kansas and the founding of the Republican Party. The Dred Scott decision (1857) said Congress could not ban slavery in the territories, and John Brown raided Harpers Ferry in 1859. Lincoln won in 1860 without a single Southern electoral vote, and South Carolina seceded that December.
Lincoln and the Republicans did not propose ending slavery in the South in 1860, so why did Southern states secede? Republicans opposed slavery's expansion, and Southern leaders believed that blocking expansion would eventually doom slavery and leave the South outvoted in a growing Union. They no longer trusted the federal government to protect slavery.
| Measure | Year | What it did | Why it raised tensions |
|---|---|---|---|
| Missouri Compromise | 1820 | Admitted Missouri (slave) and Maine (free); banned slavery in Louisiana Purchase territory north of 36°30', except Missouri | Drew a sectional line across the map and showed how explosive expansion could be |
| Compromise of 1850 | 1850 | Admitted California as free; let Utah and New Mexico decide by popular sovereignty; passed the Fugitive Slave Act | The Fugitive Slave Act forced Northerners to take part in slavery and angered many who had been neutral |
| Kansas-Nebraska Act | 1854 | Let settlers in Kansas and Nebraska decide on slavery, repealing the Missouri Compromise's restriction on slavery north of 36°30' | Opened land once promised to freedom, led to violence in Kansas, and split the old party system |
The Second Great Awakening was a wave of Protestant revivals from about the 1790s to the 1840s. Preachers such as Charles Finney led emotional revival meetings and taught that people could choose salvation. That teaching differed from the Calvinist belief that God had already decided who would be saved, though some Calvinists also took part in revivals. Western New York saw so many revivals that it was nicknamed the "burned-over district." Methodists and Baptists grew fastest, and new faiths emerged, including the Church of Jesus Christ of Latter-day Saints, founded by Joseph Smith.
If individuals could improve themselves, many believers reasoned, society could be improved too. This idea, called perfectionism, powered reform. The American Temperance Society (1826) campaigned against heavy drinking, and Maine restricted alcohol sales in 1851, with exceptions for uses such as medicine. Horace Mann built tax-supported common schools in Massachusetts. Dorothea Dix pushed states to build hospitals for the mentally ill instead of jailing them.
The women's rights movement grew out of abolition. After women delegates were barred from full participation at the 1840 World Anti-Slavery Convention in London, Elizabeth Cady Stanton and Lucretia Mott organized the Seneca Falls Convention in 1848. Its Declaration of Sentiments stated that "all men and women are created equal," and its call for voting rights was the most controversial resolution there.
Not all reformers were evangelicals. Transcendentalists like Ralph Waldo Emerson and Henry David Thoreau stressed individual conscience, and Thoreau's "Civil Disobedience" (1849) protested slavery and the Mexican-American War.
How did the Second Great Awakening contribute to the coming of the Civil War? Revival preaching encouraged many Northerners to confront slavery as a moral evil. That made compromise harder, while many Southern churches and politicians defended slavery.
| Term | Definition |
|---|---|
| Antebellum | Latin for "before the war," used for the period from roughly 1815 to the start of the Civil War in 1861. |
| Market revolution | The rise of a national economy based on producing goods for sale, driven by canals, railroads, and factories. |
| Manifest Destiny | The belief that the United States was destined by God to expand across North America. |
| Sectionalism | Loyalty to one's own region, such as the North or South, over the nation as a whole. |
| Popular sovereignty | The policy of letting settlers in a territory vote on whether to allow slavery, promoted by Senator Stephen Douglas. |
| Wilmot Proviso | A failed 1846 proposal to ban slavery in any land gained from Mexico, which passed the House but repeatedly failed in the Senate. |
| Moral suasion | The abolitionist strategy of changing public opinion through speeches, newspapers, and petitions that appealed to conscience. |
| Underground Railroad | A loose network of people and safe houses that helped enslaved people escape to the free states and Canada. |
| Secession | The formal withdrawal of a state from the Union, beginning with South Carolina in December 1860. |
It's easy to read the North as uniformly against slavery, but abolitionists were a small and often unpopular minority, and mobs attacked them in Northern cities. Most antislavery Northerners were free-soilers who wanted slavery kept out of the West, often to protect opportunities for white workers. The Republican Party of 1860 ran on stopping expansion, not on ending slavery in the South.
Because it was a labor-saving machine, people guess the gin reduced the need for enslaved workers. The reverse happened. It made cotton so profitable that planters expanded onto millions of new acres, and the enslaved population grew from about 700,000 to nearly 4 million.
The Missouri Compromise (1820) used a map line at 36°30'. The Compromise of 1850 used popular sovereignty for Utah and New Mexico and enacted a stricter Fugitive Slave Act. The Kansas-Nebraska Act (1854) applied popular sovereignty to land north of the old line and repealed the Missouri Compromise's restriction on slavery there. A quick way to keep them straight is to ask whether each one used a line or a vote.
Manifest Destiny was a belief in US expansion, not a law. The phrase was coined in 1845. Plenty of Americans objected to how it was carried out. Many Whigs opposed the Mexican-American War, and a young congressman named Abraham Lincoln challenged Polk to show the exact "spot" where American blood had been shed on American soil.