Heimler's History: Mexican American War

Introduction

• Continuation of Unit 5 in AP U.S. History
• Focus: Causes and effects of the Mexican American War

Causes of the Mexican-American War

Texas Independence and Annexation

• Texas declared independence from Mexico in 1836; fought battles against Mexico
• Tensions existed between Texas and Mexico post-independence
• Texas preferred annexation by the U.S., opposed by Mexico
• Presidents Jackson, Van Buren, Harrison, and Tyler avoided annexation
• James K. Polk elected in 1845, promised and pursued Texas annexation
• John Tyler initiated annexation on his way out of office, influenced by Polk's election

Diplomatic Tensions

• Polk sent John Slidell to Mexico:
  • Task 1: Purchase New Mexico and California - Mexican authorities refused
  • Task 2: Define southern border - Disagreement over Nueces River (Mexico) vs. Rio Grande (U.S.)
• Polk escalated by stationing American troops at Rio Grande
• Conflict led to 11 Americans dead; Polk sought declaration of war
• Congress declared war on May 13, 1846

Effects of the Mexican-American War

Territorial Gains

• Treaty of Guadalupe Hidalgo (1848) signed
  • Established Rio Grande as Texas' southern border
  • Mexican Cession: California and New Mexico ceded to U.S. for $15 million
• Gadsden Purchase (1853) added to U.S. territory
• Mexico lost over half of its territory

Wilmot Proviso

• Proposed by David Wilmot in 1846
• Sought to prohibit slavery in territories won from Mexico
• Voted down, but highlighted tensions over slavery
• Some historians mark it as an early step towards Civil War

Impact on Non-American Residents

• Many Mexicans and Indians remained in ceded territories
• Treaty of Guadalupe Hidalgo granted U.S. citizenship to Mexicans, not Indians
• Indians faced discrimination, delayed citizenship until 1930s
• Both groups experienced civil rights challenges, including voter discrimination and educational segregation

Conclusion

• Overview of Unit 5, Topic 3 in AP U.S. History
• Encouragement for successful study and exam results