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5.1 Westward Expansion and Immigration

Jun 11, 2025

Overview

This lecture covers APUSH Period 5 Key Concept 5.1, focusing on Manifest Destiny, westward expansion, immigration, and their economic, political, and social consequences in the United States from the 1840s–1870s.

Immigration and Nativism

  • Large waves of Irish immigrants arrived due to famine in the 1840s, settling mainly in Northern cities and working unskilled jobs.
  • Competition for jobs between Irish immigrants and African Americans fueled racial tensions in the North.
  • Irish immigrants largely supported the Democratic Party and influenced political machines like Tammany Hall.
  • German immigrants were diverse in religion and class and settled mainly in the Old Northwest, forming tight-knit communities.
  • Nativist (anti-immigrant) sentiment rose, driven by fears about job competition, political influence, and cultural change.
  • The Know-Nothing Party formed, advocating for immigration restrictions.

Manifest Destiny & Territorial Expansion

  • Manifest Destiny was the belief that Americans were destined to expand across the continent, justified by ideas of racial superiority.
  • U.S. acquired Oregon (1846), annexed Texas (1845), and gained vast southwestern lands after the Mexican-American War (Treaty of Guadalupe Hidalgo, 1848).
  • Expansion brought new territories and forced the issue of slavery into national politics, increasing sectionalism.

Western Migration and Economic Opportunity

  • Groups including Mormons (to Utah, 1847) and Gold Rush seekers (to California, 1848) moved west seeking religious freedom and economic opportunities.
  • The west attracted not only white Americans but also African Americans and immigrants from Asia and other regions.
  • The federal government promoted western development through acts like the Pacific Railroad Act (1862) and Homestead Act (1862).

Economic Development and Environmental Impact

  • Railroads, funded by federal subsidies, connected the West to national markets.
  • Mining booms, such as the California Gold Rush and Comstock Lode, drove population growth and economic development.
  • The Homestead Act encouraged farming on the Great Plains, leading to significant westward migration.
  • Expansion caused environmental changes: buffalo population collapse and soil erosion due to over-farming.

Conflict and Cultural Change in the West

  • Westward expansion led to violent conflict with Native Americans (e.g., Sand Creek Massacre 1864, Battle of Little Bighorn 1876).
  • Native Americans faced pressure to assimilate or move onto reservations.
  • Hispanic Californios lost land rights after the U.S. acquisition of the Southwest, though Latino culture persisted in the region.

U.S. Expansion and Trade with Asia

  • Faster clipper ships and new treaties expanded U.S. trade with China (first treaty, 1844) and opened Japan (Commodore Perry, 1852).
  • U.S. missionaries went to China and Japan to spread Christianity and foster cultural ties.

Key Terms & Definitions

  • Manifest Destiny — belief that Americans were destined to expand across North America.
  • Nativism — anti-immigrant sentiment favoring native-born citizens.
  • Homestead Act (1862) — law granting 160 acres of land to settlers who farmed it for five years.
  • Pacific Railroad Act (1862) — law authorizing construction of a transcontinental railroad.
  • Treaty of Guadalupe Hidalgo (1848) — ended the Mexican-American War, ceding vast territories to the U.S.
  • Know-Nothing Party — political party advocating for immigration restrictions.
  • Sectionalism — increased regional tension, especially over slavery, between North and South.

Action Items / Next Steps

  • Review Key Concept 5.2 on sectionalism and the impact of expansion on national unity.
  • Study the details of major legislative acts (Homestead Act, Pacific Railroad Act) and their impact on westward expansion.
  • Prepare to identify causes and consequences of westward migration for different groups.