Topic 5.2 Notes – Manifest Destiny

What Manifest Destiny Meant

Manifest Destiny was the belief that the U.S. had a God-given mission and right to expand west. John L. O’Sullivan coined the phrase in 1845 during the debate over annexing Texas, but the idea built on older expansion. The difference in the 1840s was that continental expansion became a central national goal.

This idea bundled several beliefs together:

• American exceptionalism said U.S. institutions were superior and worth spreading.
• Republican government, private property, Protestant Christianity, and capitalism were treated as signs of “civilization.”
• Jefferson’s empire of liberty linked landownership to independent citizens and a healthy republic.
• Nationalism pushed Americans to block British, Mexican, and other foreign influence.
• White racial assumptions let expansionists dismiss Native and Mexican sovereignty.

John Gast’s American Progress captures how supporters imagined that mission, with settlers, farms, transportation, and communications pushing west as Native peoples and bison are driven back.

American Progress and Manifest Destiny

Manifest Destiny gave moral cover to expansion, but people also moved for very practical reasons like land, profit, and refuge.

• Democrats, especially James K. Polk, strongly backed expansion.
• Whigs often saw aggressive expansion as dangerous and reckless.
• Antislavery Northerners feared new slave territory.
• Native peoples and Mexicans resisted losing land and self-rule.

Why Americans Moved West

People rarely moved west for one reason. Economic opportunity, resources, religion, and escape from old limits all worked together.

• Cheap, fertile land attracted farmers shut out of eastern land markets.
• Texas drew cotton planters, cattle raisers, and speculators.
• Oregon offered rich farmland, forests, rivers, and Pacific access.
• Timber, grazing land, and gold promised wealth.
• Mormons wanted religious refuge.
• Trade and commerce pulled merchants west.
• Some migrants wanted to escape debt, crowding, and old hierarchies.

Major migrations

• California Gold Rush began after Sutter’s Mill in 1848. The huge wave in 1849 produced the name forty-niners.
• After Joseph Smith’s death, Brigham Young led Mormons to the Great Salt Lake in 1847, where they used irrigation and planned settlement.

Overland routes

These migration routes linked starting points in the Midwest to destinations in Oregon, California, the Great Salt Lake, and Santa Fe.

• Oregon Trail
• California Trail
• Mormon Trail
• Santa Fe Trail

Major overland trails to the West

A common test trap is overplaying Native attacks. On most journeys, the routine dangers were disease, accidents, weather, and shortages.

How the United States Expanded West in the 1840s and 1850s

The main gains came in sequence, and this map helps you see how each addition built the continental United States:

1. Texas annexation in 1845
2. Oregon Treaty in 1846
3. Mexican Cession in 1848
4. Gadsden Purchase in 1853

Major U.S. territorial acquisitions

• Texas had been independent from Mexico since 1836. John Tyler annexed it by joint resolution, and many Northerners saw it as pro-slavery expansion. It helped trigger the Mexican-American War.
• Oregon had been jointly occupied by Britain and the U.S. since 1818. “Fifty-four Forty or Fight!” showed expansionist pressure, but Polk compromised at the 49th parallel in the Oregon Treaty. That is the clearest diplomacy example.
• The Mexican Cession gave the U.S. California and much of the Southwest.
• The Gadsden Purchase added land useful for a southern transcontinental railroad.
• California became the clearest resource-driven case. Gold plus U.S. control brought massive migration, San Francisco exploded in growth, and California entered as a free state in 1850, worsening sectional tension.

What Expansion Cost and What It Changed

Expansion meant conflict over who controlled land.

• Native nations already lived on and used western lands. Settlers, miners, ranchers, and railroads disrupted water, game, movement, and treaty lines. U.S. policy moved toward reservations. Native responses included negotiation, adaptation, migration, and armed resistance.
• Mexicans in annexed lands often lost property through fraud, taxes, legal disputes, and violence.

The federal government heavily promoted western growth:

• Homestead Act (1862) gave settlers 160 acres.
• Pacific Railway Acts (1862, 1864) funded the transcontinental railroad. Union Pacific and Central Pacific met at Promontory Summit in 1869. Labor came heavily from Irish and Chinese workers.
• Morrill Land-Grant Act (1862) supported colleges in agriculture and mechanics.

Expansion also tied the U.S. to Asia:

• Treaty of Wangxia (1844) opened trade with China.
• Matthew Perry forced opening with Japan through the Treaty of Kanagawa (1854).
• The U.S. built stronger trade and missionary ties with Hawaii.
• Alaska was bought in 1867 and mocked as “Seward’s Folly.”