The American Yawp — Chapter Eleven: Growth and Conflict
Abridged for Intermediate-High Learners

In the 1830s and 1840s, America changed with stunning speed. The railroad spread across the country — Americans laid more than thirty thousand miles of track. Canals, roads, and faster communication connected farms to cities and the nation to the world. Cotton, picked by the hands of enslaved Black workers in the South, powered much of the economy and was shipped to factories in the North and in Britain.

Industry created new problems. In Massachusetts, young women working in the Lowell textile mills organized a strike and formed the Lowell Female Labor Reform Association to demand better pay and hours. Middle-class women were expected to devote themselves to home and family, an ideal called domesticity. Workers won small victories: President Martin Van Buren set a ten-hour day for laborers on federal projects, and New Hampshire and Pennsylvania passed labor laws.

Religion changed too. Joseph Smith founded the Mormon church; after Smith was killed in 1844, Brigham Young led the Mormons west beginning in 1846. The Transcendentalists, including Ralph Waldo Emerson and Henry David Thoreau, celebrated nature and individualism. In his 1849 essay "Resistance to Civil Government," Thoreau argued that people should follow their conscience even against the law.

Reform movements grew bolder. Frederick Douglass escaped from slavery and became a leading abolitionist; his Narrative of the Life of Frederick Douglass, published in 1845, was read around the world. In 1848, Elizabeth Cady Stanton and Lucretia Mott organized the Seneca Falls Convention in New York, the first convention for women's rights. Stanton wrote the Declaration of Sentiments, modeled on the Declaration of Independence, demanding equality — including, controversially, the right to vote. Sixty-eight women and thirty-two men signed it.

Meanwhile, Americans pushed west, driven by "manifest destiny" — the belief that the United States was destined to spread across the continent. But the West was not empty. Powerful Indigenous nations controlled much of it. On the Southern Plains, the Comanche built a vast trading empire on horseback and resisted both Mexican and American settlers. Meanwhile, thousands of American families traveled west in wagon trains during the 1840s, seeking farmland in Oregon Country. Many expansionists joined the Young America movement, which celebrated democracy and national progress. Critics such as Ralph Waldo Emerson, however, warned that aggressive expansion was greedy and unjust.

Texas had won independence from Mexico in 1836, and the United States voted to annex Texas in 1845. President James K. Polk, elected in 1844, wanted still more land. Texas and Mexico had a border dispute: Mexico drew it at the Nueces River, while Texans claimed the Rio Grande, 150 miles farther west. Polk sent General Zachary Taylor's army into the disputed land, fighting began, and Congress declared war in 1846. The US-Mexican War was brutal — disease killed seven times as many American soldiers as combat did.

Peace came with the Treaty of Guadalupe Hidalgo on February 2, 1848. The United States gained California, Utah, Nevada, most of Arizona, and parts of New Mexico, Colorado, and Wyoming, and Mexico gave up its claims to Texas. But the vast new land reopened a bitter question: would slavery expand west? The Free Soil Party, formed in 1848, demanded that the new lands stay open to free workers, not slavery. In the election of 1848, the Whig general Zachary Taylor defeated Democrat Lewis Cass and Free Soil candidate Martin Van Buren. Growth had brought conflict, and the nation was splitting over slavery.