🌎

Westward Expansion and Key Events

Sep 22, 2025

Overview

This lecture covers Manifest Destiny, westward expansion, the Texas War for Independence, and the political developments tied to U.S. territorial growth in the mid-1800s.

Manifest Destiny and Westward Expansion

  • Manifest Destiny was the belief that Americans were destined by God to expand westward across the continent.
  • This expansion aimed to spread Protestant Christianity, capitalism, liberty, and prosperity.
  • Westward movement oppressed minorities, including Native Americans, African Americans, and immigrant laborers.
  • Missouri was the main jumping-off point for western migration, with trails like the Oregon, California, Mormon, Santa Fe, and Old Spanish serving as primary routes.
  • Life on the trail was dangerous, with risks from disease, weather, accidents, and lack of supplies.
  • Women often broke gender norms, taking on roles traditionally held by men, fueling early women’s rights movements in the West.
  • The Donner Party tragedy exemplified the extreme hardships and dangers faced by migrants.

Gold Rush and the California Frontier

  • Gold was discovered in 1848 at Sutter's Mill, leading to a massive influx of settlers during the California Gold Rush.
  • The Gold Rush boosted the U.S. economy and sped California’s path to statehood.
  • The influx of settlers caused the California Genocide, with mass violence and displacement against Native Americans.

Texas War for Independence

  • American settlers (Texians) moved illegally into Mexican Texas, often bringing slaves despite Mexican law.
  • By 1835, Texians outnumbered Tejanos 10 to 1 and began pushing for independence.
  • Antonio Lopez de Santa Anna became dictator of Mexico and acted harshly against the Texians.
  • Key battles included the Alamo (Texan defeat and rallying cry) and Goliad Massacre (mass execution of Texan prisoners).
  • Sam Houston led Texan forces to victory at the Battle of San Jacinto, capturing Santa Anna and securing Texas independence.
  • Texas became the Republic of Texas, legalized slavery, and requested U.S. annexation.

Political Developments and Expansionism

  • Presidents Harrison (died after 31 days) and Tyler (who pushed for Texas annexation) were significant figures of this period.
  • Tyler’s effort to annex Texas succeeded by passing a treaty resolution.
  • The Creole slave ship revolt led to freed slaves in British Bahamas, creating a U.S.-UK diplomatic crisis.
  • The presidential election of 1844 saw James K. Polk win with promises of expansion, lowered tariffs, and acquiring California.
  • Polk settled the Oregon boundary with Britain at the 49th parallel and restored an independent treasury.
  • Tensions with Mexico over Texas’ border led Congress to declare war against Mexico in 1846.

Key Terms & Definitions

  • Manifest Destiny — the belief that U.S. expansion westward was justified and inevitable.
  • Oregon Trail — major route used by pioneers migrating west.
  • Texians — American settlers living in Mexican Texas.
  • Tejanos — Mexican residents of Texas.
  • The Alamo — site of a pivotal siege and battle in the Texas Revolution.
  • Goliad Massacre — execution of Texan prisoners by Mexican forces.
  • Republic of Texas — independent nation formed after winning independence from Mexico.
  • Annexation — the act of adding territory to a country.
  • California Gold Rush — a period of mass migration to California after gold was discovered.
  • Polk’s Presidency — marked by territorial expansion and fulfillment of campaign promises.

Action Items / Next Steps

  • Review the details and consequences of the U.S.-Mexican War for next lecture.
  • Complete discussion board post relating to life on the Oregon Trail.
  • Prepare for discussion on the impact of territorial expansion on slavery.