Conclusion: The Effects of Westward Expansion

Conclusion: The Effects of Westward Expansion

The United States’ militant westward expansion in the 19th century profound affected American Indians and contributed to tensions over slavery.

Learning Objectives

Summarize how westward expansion changed the United States geographically, demographically, militarily, and politically

Key Takeaways

Key Points

  • Rooted in the idea of manifest destiny, the United States militantly expanded westward across the continent in the 19th century.
  • Americans saw their nation’s mission as one of bringing education, modern technology, and civilization to the West and driving away the “uncivilized” American Indians.
  • In the mid-19th century, the quest for control of the West led to the annexation of Texas and the Mexican–American War.
  • Efforts to seize western territories from native peoples and expand the republic by warring with Mexico succeeded beyond expectations; few nations had ever expanded so quickly.
  • This expansion led to debates about the fate of slavery in the West, increasing tensions between the North and South that ultimately led to the collapse of American democracy and a brutal civil war.

Key Terms

  • manifest destiny: A widely held belief in the 19th century United States that its settlers were given the divine right to expand across the continent.
  • Columbia: A historical and poetic name used for the United States of America and also as one of the names of its female personification.

After 1800, the United States militantly expanded westward across the continent. Rooted in the idea of manifest destiny, the United States considered it a God-given right and duty to gain control of the continent and spread the benefits of its “superior” culture. Illustrated by the white, blonde, feminine figure of Columbia, the historical personification of the United States, people saw the nation’s mission as one of bringing education, modern technology, and civilization to the West and driving away the “uncivilized” American Indians.

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Columbia and Westward Expansion: In the first half of the 19th century, settlers began to move west of the Mississippi River in large numbers. In John Gast’s American Progress (ca. 1872), the figure of Columbia, representing the United States and the spirit of democracy, makes her way westward, literally bringing light to the darkness as she advances.

In the mid-19th century, the quest for control of the West led to the annexation of Texas and the Mexican–American War. President James Polk’s administration (1845–1849) was a period of intensive expansion for the United States. After overseeing the final details regarding the annexation of Texas from Mexico, Polk negotiated a peaceful settlement with Britain regarding ownership of the Oregon Country, which delivered to the United States what are now Washington and Oregon.

The acquisition of additional lands from Mexico, a country many in the United States perceived as weak and inferior, was not so bloodless and culminated in the Mexican–American War. After U.S. victory, the Mexican Cession added nearly half of Mexico’s territory to the United States, including New Mexico and California, and established the U.S.–Mexico border at the Rio Grande. The California Gold Rush of 1849 rapidly expanded the population of the new territory, while also prompting concerns over immigration, especially from China.

Efforts to seize western territories from native peoples and expand the republic by warring with Mexico succeeded beyond expectations; few nations had ever expanded so quickly. However, this expansion led to debates about the fate of slavery in the West. Increasingly, the South came to regard itself as under attack by radical northern abolitionists, and many northerners began to speak ominously of a southern drive to dominate U.S. politics for the purpose of protecting slaveholders’ human property. As tensions mounted and both sides hurled accusations, national unity frayed. Compromise became nearly impossible and antagonistic sectional rivalries replaced the idea of a unified, democratic republic. Tensions between the North and South ultimately led to the collapse of American democracy and a brutal civil war.