Expansion and Manifest Destiny

The following notes will help you prepare for questions about the expansion of the U.S. and Manifest Destiny on the AP U.S. History Exam.

  • In the years before the Civil War, the U.S. expanded significantly. Manifest Destiny, or the idea that it was the God-given right of white settlers to settle the West, was the driving force behind expansion. This expansion came at the cost of Native Americans, who were forced off their land and, eventually, onto reservations.

  • The U.S. obtained a large portion of the Southwest after defeating Mexico in the Mexican-American War, which lasted from 1846 - 1848. The U.S. provoked an attack by sending troops into disputed territory south of the Rio Grande, under the orders of President James Polk.

  • The U.S. also experienced an increase in immigration during this time, leading to a wave of nativism. Many of the immigrants were from Ireland as they were escaping a deadly famine that took hold of their country.


The Alamo : site of rebellion by Americans living in San Antonio

Compromise of 1850 : permitted California to enter the Union as a free state, ended the slave trade in Washington, D.C., created a newer, stronger fugitive slave law to appease the southern states

Dorothea Dix : activist who worked on behalf of the mentally ill

Gadsen Purchase : the sale of portions of southern Arizona and New Mexico from Mexico to the U.S. to allow the U.S. to build a southern transcontinental railroad

Irish potato famine : diseased potato crops in Ireland sent a wave of immigrants into the U.S.

Know-Nothings : political party of the mid-19th century, noted for its anti-Catholic and anti-immigrant beliefs

nativism : a movement with hostility toward immigrants at its core

sectionalism : the division between the northern states and southern states, each concerned for what was in their own best interest

Treaty of Guadalupe Hidalgo : Ended the Mexican-American War; Mexico ceded almost all of its land from Texas to California for $15 million

transcendentalism : philosophical movement that argued that political parties and organized religion were corrupting

Wilmot Proviso : failed bill introduced by Congressman David Wilmot that would have banned slavery in land acquired from Mexico

Whigs : political party that opposed annexation and acquiring new land because it created sectionalism; catered to immigrant voters

People :

John C. Fremont : American general and explorer; became the Republican Party's first presidential candidate

John O'Sullivan : Journalis who coined the phrase "manifest destiny"

James Polk : 11th president of the U.S.; many of his actions and policies favored expanding the U.S.

Henry David Thoreau : transcendentalist who advocated for non-violent civil disobedience


Related Links:
Gilded Age Quiz
AP US History Quizzes
AP US History Notes
Westward Expansion Facts
Westward Expansion Timeline
Exploration and Colonization
Gilded Age

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