US History – Before 1865

🦬US History – Before 1865 Unit 9 – Manifest Destiny & Western Expansion

Manifest Destiny drove America's westward expansion in the 19th century. This belief in the nation's right to spread across the continent fueled territorial acquisitions, conflicts with Native Americans and Mexico, and rapid settlement of new lands. The push west reshaped America's boundaries, economy, and identity. It led to the displacement of Native peoples, debates over slavery's expansion, and the transformation of vast territories into new states and economic frontiers.

Key Concepts and Definitions

  • Manifest Destiny: belief that the United States was destined to expand across the North American continent
  • Westward Expansion: movement of American settlers into the western territories of the United States during the 19th century
  • Louisiana Purchase (1803): acquisition of territory from France that doubled the size of the United States
  • Oregon Trail: 2,000-mile overland route used by settlers traveling from Missouri to Oregon Country
  • Mexican-American War (1846-1848): conflict between the United States and Mexico resulting in significant territorial gains for the U.S.
  • Treaty of Guadalupe Hidalgo (1848): agreement that ended the Mexican-American War and ceded vast territories to the United States
  • Gadsden Purchase (1853): acquisition of land from Mexico that became part of Arizona and New Mexico

Historical Context and Origins

  • Rooted in the idea of American exceptionalism and the belief in the superiority of American democracy and institutions
  • Fueled by population growth, economic opportunities, and technological advancements (steamboats, railroads)
  • Influenced by the Second Great Awakening, which emphasized the importance of spreading Protestant Christianity
  • Justified by the concept of "Manifest Destiny," a term coined by journalist John O'Sullivan in 1845
  • Supported by politicians like Andrew Jackson and James K. Polk, who advocated for territorial expansion
  • Driven by the desire for new agricultural lands, natural resources, and access to Pacific trade routes
  • Shaped by the idea of the "frontier" as a defining feature of American identity and character

Major Events and Milestones

  • Louisiana Purchase (1803) doubled the size of the United States and opened up vast new territories for settlement
  • Lewis and Clark Expedition (1804-1806) explored and mapped the newly acquired Louisiana Territory
  • Adams-Onis Treaty (1819) established the border between the United States and Spanish Florida
  • Indian Removal Act (1830) authorized the forced relocation of Native American tribes from the Southeast to the West
  • Texas Revolution (1835-1836) resulted in the independence of Texas from Mexico
  • Oregon Treaty (1846) established the 49th parallel as the border between the United States and British Canada in the Pacific Northwest
  • California Gold Rush (1848-1855) attracted thousands of settlers and accelerated westward migration
  • Compromise of 1850 addressed the issue of slavery in the newly acquired territories and delayed the onset of the Civil War

Key Figures and Their Roles

  • Thomas Jefferson: orchestrated the Louisiana Purchase and commissioned the Lewis and Clark Expedition
  • Meriwether Lewis and William Clark: led the expedition that explored and mapped the Louisiana Territory
  • Andrew Jackson: advocated for the removal of Native American tribes and signed the Indian Removal Act
  • Stephen F. Austin: known as the "Father of Texas" for his role in establishing American settlements in Mexican Texas
  • Sam Houston: led the Texas Revolution and served as the first President of the Republic of Texas
  • James K. Polk: oversaw the annexation of Texas, the Oregon Treaty, and the Mexican-American War
  • John C. Frémont: explored and mapped the American West, earning the nickname "The Pathfinder"

Impact on Native American Populations

  • Westward expansion led to the displacement and forced relocation of numerous Native American tribes
  • Indian Removal Act (1830) resulted in the Trail of Tears, the forced march of the Cherokee Nation to Indian Territory (present-day Oklahoma)
  • Treaties were often used to acquire Native American lands, but these agreements were frequently violated or ignored by the U.S. government and settlers
  • Native Americans faced loss of land, resources, and traditional ways of life as settlers encroached upon their territories
  • Conflicts and wars erupted between Native American tribes and U.S. forces (Seminole Wars, Black Hawk War)
  • Reservation system established to confine Native American populations to designated areas
  • Cultural assimilation policies aimed to eradicate Native American languages, religions, and customs

Territorial Acquisitions and Conflicts

  • Louisiana Purchase (1803) acquired from France, doubling the size of the United States
  • Florida acquired through the Adams-Onis Treaty (1819) with Spain
  • Texas annexed in 1845 after gaining independence from Mexico
  • Oregon Country jointly occupied with Britain until the Oregon Treaty (1846) established the 49th parallel border
  • Mexican-American War (1846-1848) resulted in the acquisition of vast territories, including California and the American Southwest
  • Gadsden Purchase (1853) acquired additional land from Mexico for a southern transcontinental railroad route
  • Conflicts with Native American tribes (Seminole Wars, Black Hawk War) as settlers encroached upon their territories

Economic and Social Consequences

  • Expansion of agriculture and the cotton industry in the South, fueled by slave labor
  • Growth of the mining industry, particularly after the California Gold Rush (1848-1855)
  • Development of transportation infrastructure (canals, railroads) to connect eastern markets with western resources
  • Increased sectional tensions between the North and South over the issue of slavery in the new territories
  • Displacement and forced relocation of Native American populations, disrupting their traditional ways of life
  • Influx of diverse immigrant populations in the West, including Chinese laborers and European settlers
  • Growth of cities and towns along the frontier, serving as hubs for trade and commerce

Legacy and Long-Term Effects

  • Manifest Destiny and westward expansion shaped the geographical boundaries of the modern United States
  • Acquisition of new territories led to debates over the extension of slavery, contributing to the onset of the Civil War
  • Displacement and oppression of Native American populations had lasting effects on their communities and cultures
  • Economic development of the West transformed the nation, providing new resources and markets
  • Idea of the "frontier" became a central theme in American culture, literature, and identity
  • Legacy of racial and ethnic diversity in the American West, with lasting impacts on social and political dynamics
  • Environmental consequences of rapid settlement and resource exploitation, including deforestation and wildlife depletion


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© 2024 Fiveable Inc. All rights reserved.
AP® and SAT® are trademarks registered by the College Board, which is not affiliated with, and does not endorse this website.