6.3 Territorial Expansion and Manifest Destiny

The United States rapidly expanded its territory in the early 19th century. The Louisiana Purchase, Texas annexation, and Mexican-American War added vast lands to the nation. These acquisitions fueled the belief in Manifest Destiny and American exceptionalism.

Territorial expansion had profound impacts on Native Americans and sectional tensions over slavery. The displacement of indigenous peoples and debates over slavery in new territories intensified conflicts between North and South, setting the stage for future crises.

Antebellum Territorial Expansion

Louisiana Purchase and Adams-Onis Treaty

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• The Louisiana Purchase in 1803 nearly doubled the size of the United States, adding territory from the Mississippi River to the Rocky Mountains
• The Adams-Onis Treaty of 1819 ceded Florida to the United States from Spain and established the boundary between the U.S. and New Spain

Texas Annexation, Oregon Boundary, and Mexican-American War

• The annexation of Texas in 1845 and the resolution of the Oregon boundary dispute with Britain in 1846 further expanded U.S. territory
• The Mexican-American War (1846-1848) resulted in the acquisition of vast territories in the Southwest and California through the Treaty of Guadalupe Hidalgo
• The Gadsden Purchase in 1853 acquired additional land from Mexico in present-day southern Arizona and New Mexico (Sonora and Chihuahua)

Manifest Destiny's Influence

Belief in Divine Right and Duty

• Manifest Destiny was the belief that the United States was destined by God to expand its dominion and spread democracy and capitalism across the entire North American continent
• This ideology was used to justify westward expansion, as many Americans believed it was their divine right and duty to extend the "boundaries of freedom" to the Pacific Ocean

American Exceptionalism and Racial Superiority

• Manifest Destiny was influenced by the idea of American exceptionalism, which held that the United States was inherently different from other nations due to its republican ideals, economic opportunity, and expansive territories
• The concept was often associated with the belief in the racial and cultural superiority of white Americans over Native Americans and Mexicans (Anglo-Saxonism)
• Manifest Destiny shaped American foreign policy, leading to increased territorial acquisitions, diplomatic initiatives, and military interventions in the Western Hemisphere (Monroe Doctrine)

Territorial Acquisition's Impact

Native American Displacement and Conflicts

• Westward expansion and territorial acquisition led to the displacement and forced relocation of numerous Native American tribes
• The Indian Removal Act of 1830 authorized the president to negotiate treaties to remove Native American tribes living east of the Mississippi River and relocate them to federal territory west of the river
  • This policy resulted in the Trail of Tears, the forced migration of Cherokee, Muscogee, Seminole, Chickasaw, and Choctaw nations from their ancestral homelands to Indian Territory (present-day Oklahoma)
• As American settlers moved westward, conflicts with Native American tribes intensified, leading to a series of wars and skirmishes, such as the Black Hawk War (1832) and the Second Seminole War (1835-1842)

Sectional Tensions over Slavery

• The expansion of slavery into newly acquired territories exacerbated sectional tensions between the North and the South
  • The Missouri Compromise (1820) attempted to maintain the balance between free and slave states, but the issue of slavery in the territories remained contentious
  • The Wilmot Proviso (1846), which sought to ban slavery in any territory acquired from Mexico, further heightened sectional tensions
• The Compromise of 1850 attempted to resolve the issue of slavery in the territories, but it ultimately failed to address the underlying causes of sectional conflict (popular sovereignty)

Mexican-American War Consequences

Territorial Gains and Debates over Slavery

• The Mexican-American War resulted in the U.S. acquisition of a vast territory, including present-day California, Nevada, Utah, and parts of Arizona, New Mexico, Colorado, and Wyoming
• The war and subsequent territorial gains reignited debates over the extension of slavery into new territories, contributing to the growing sectional divide between the North and the South

Economic and Social Transformations

• The discovery of gold in California in 1848 led to the California Gold Rush, which brought a massive influx of settlers and transformed the region's economy and demographics
• The war and territorial acquisitions accelerated westward migration and the displacement of Native American populations, as American settlers sought to establish farms, ranches, and communities in the newly acquired lands (Homestead Act)

Political and Cultural Impact

• The Treaty of Guadalupe Hidalgo (1848) ended the war and guaranteed U.S. citizenship and property rights to Mexicans living in the ceded territories, but many faced discrimination and loss of land in the following decades
• The war had political consequences, with the Whig Party opposing the war and the expansionist policies of President James K. Polk, while Democrats generally supported the war effort and territorial expansion