Lecture on President James K. Polk's Expansion Goals and the Mexican-American War

Polk's Fourth Goal: Acquisition of California and New Mexico

• In 1846, President James K. Polk sought to acquire California and New Mexico from Mexico.
• Slidell Mission:
  • John Slidell was sent to negotiate with Mexico.
  • Offered $5 million for New Mexico and $25 million for California.
  • Mexico rejected the offer and demanded the U.S. return Texas.
  • Slidell was expelled from Mexico City, escalating tensions.

Causes of the Mexican-American War

1. Failed Negotiations and Mexican Concerns:
   • Slidell's failed mission heightened Mexican suspicions of U.S. intentions to seize land.
2. Border Dispute:
   • Conflict over the Texas-Mexico border: Texas claimed the Rio Grande, while Mexico claimed the Nueces River.
   • Polk ordered General Zachary Taylor to move to the Rio Grande, exacerbating tensions.
   • Battle of Palo Alto:
     • Occurred between Brownsville and South Padre Island.
     • Zachary Taylor won, marking the opening battle of the war.
   • Perception of invasion by both nations as clashes over the Rio Grande occurred.

Outbreak and Course of the War

• Congress declared war on Mexico on May 13, 1846.
• The war was overwhelmingly in favor of the U.S.
• U.S. forces secured victories in northern Mexico and captured New Mexico and California.
• Treaty of Guadalupe Hidalgo ended the war:
  • U.S. gained control over Texas, New Mexico, California, Arizona, Colorado, Utah, Nevada, and part of Wyoming.
  • U.S. paid Mexico $18 million and forgave $3 million in debt.
  • Established the Rio Grande as the Texas-Mexico border.

Results and Significance of the War

1. Territorial Changes:
   • Mexico lost half of its territory.
   • U.S. gained modern borders with the Pacific Ocean.
2. California Gold Rush:
   • Discovery of gold in California in 1848 led to massive migration.
   • Opened new trade routes and expanded U.S. exploration in the Pacific.
3. Slavery Question:
   • New territories reopened the debate over slavery.
   • The Missouri Compromise and new lands above the 36°30' line led to Congressional disputes.
   • Polk hoped the war would strengthen the Union, but it sparked issues leading to the Civil War.

Summary

• The Mexican-American War was a significant event in U.S. history, leading to major territorial expansion and setting the stage for future conflicts over slavery.
• The lecture hints at subsequent discussions on the crises resulting from this war.