2. Manifest Destiny and the Mexican-American War

James K. Polk (1844)

Won the presidency by tapping into the powerful expansionist mood of the 1840s.

Manifest Destiny

The popular belief in American greatness and that the U.S. should expand across the continent.

John L. O'Sullivan

New York newspaper editor who coined the term 'Manifest Destiny' in 1839.

Three Pillars of Manifest Destiny

1. God's divine plan, 2. Empire of liberty, 3. Territory needed for population growth.

Jeffersonian Justification for Expansion

The belief that population growth required territorial expansion to support an agricultural society.

Reality of Manifest Destiny

Not a peaceful march of civilization, but a belligerent military conquest of lands.

Annexation of Texas (1845)

U.S. claimed Texas, which Mexico still considered its own territory, setting up a dispute.

Nueces River

The southern boundary of Texas claimed historically by Mexico.

Rio Grande

The southern boundary of Texas claimed by Texas and the United States.

John Slidell

U.S. envoy sent to offer Mexico $30 million for the Rio Grande boundary, New Mexico, and California.

Zachary Taylor (Early Role)

General sent by Polk to occupy disputed territory between the Nueces and Rio Grande.

Thornton Affair (April 1846)

A clash between U.S. and Mexican forces on disputed soil that Polk used to justify war.

Polk's War Message to Congress

Declared that 'American blood has been spilled on American soil' to secure a war declaration.

Oregon Treaty of 1846

Established the 49th parallel boundary with Canada to avoid fighting Great Britain and Mexico simultaneously.

Stephen Watts Kearny

U.S. General who successfully occupied Santa Fe, New Mexico, without much initial resistance.

Bear Flag Republic

The short-lived California republic declared by American settlers rebelling against Mexican rule.

John Charles Frémont

Led the Bear Flag Rebellion in California; later court-martialed for insubordination against Kearny.

Winfield Scott

U.S. General who captured Mexico City in 1847, forcing Mexico to negotiate a treaty.

Treaty of Guadalupe Hidalgo (1848)

Ended the Mexican-American War; signed under threat of military occupation on February 2, 1848.

Mexican Cession

The 500,000 square miles of territory (including CA and NM) surrendered by Mexico to the U.S.

U.S. Compensation to Mexico (1848)

The U.S. paid $15 million for the Mexican Cession and assumed $5 million in claims.

Mexican Landowners after 1848

Guaranteed their land by treaty, but subsequent U.S. land laws forced many to sell.