U.S. Westward Expansion & Civil War Key Figures & Events

Manifest Destiny

Belief that the U.S. was destined by God to expand across the North American continent—used to justify westward expansion and territorial conquest.

General Antonio López de Santa Anna

Mexican dictator who led forces against the Texan rebellion and at the Alamo; later defeated and captured by Sam Houston.

Sam Houston

Leader of the Texan revolution who defeated Santa Anna at San Jacinto, securing Texas independence in 1836; later became the Republic of Texas's president.

Stephen F. Austin

Leader who brought American settlers into Texas under Mexican rule; key figure in promoting U.S. settlement and eventual revolt.

Tejanos

Mexican residents of Texas who supported American settlers in the Texas Revolution but faced discrimination afterward.

Texas Annexation

The 1845 incorporation of the Republic of Texas into the U.S., sparking tensions with Mexico and contributing to the Mexican-American War.

The Alamo

Site of a major battle in 1836 where Texan rebels were defeated by Santa Anna's army; became a symbol of heroic resistance.

Oregon Border Dispute

Conflict between Britain and the U.S. over the Oregon Territory; settled by the 1846 Oregon Treaty dividing the land at the 49th parallel.

Oregon Trail

Route used by settlers moving west to Oregon and California; symbolized mass migration during the 1840s.

James K. Polk

Democratic president (1845-1849) known for territorial expansion—oversaw annexation of Texas, acquisition of Oregon, and victory in the Mexican-American War.

Mexican War

Conflict (1846-1848) between the U.S. and Mexico following Texas annexation; ended with the Treaty of Guadalupe-Hidalgo and vast U.S. territorial gains.

Zachary Taylor

General and hero of the Mexican War; later elected president in 1848 as a Whig.

Winfield Scott

U.S. general who captured Mexico City in 1847, effectively ending the Mexican-American War.

Treaty of Guadalupe-Hidalgo

1848 treaty ending the Mexican War; Mexico ceded California and New Mexico to the U.S. for $15 million.

Wilmot Proviso

Proposed ban on slavery in territories gained from Mexico; passed in the House but failed in the Senate, heightening sectional conflict.

Gold Rush

Mass migration to California after gold was discovered in 1848; led to population boom and California's statehood.

Free-Soil Party

Political party (1848-1854) opposing expansion of slavery into western territories.

Popular Sovereignty

Doctrine allowing settlers in new territories to vote on whether to allow slavery; promoted by Stephen Douglas.

Compromise of 1850

Series of laws balancing free and slave interests: California entered free; Utah and New Mexico got popular sovereignty; Fugitive Slave Act strengthened; slave trade banned in D.C.

Fugitive Slave Act

Part of the Compromise of 1850—required citizens to help capture escaped slaves; angered the North and strengthened abolitionism.

Gadsden Purchase

1853 U.S. purchase of land from Mexico (southern Arizona/New Mexico) to build a southern transcontinental railroad.

Kansas-Nebraska Act

1854 law by Stephen Douglas allowing popular sovereignty in Kansas and Nebraska; repealed the Missouri Compromise and led to 'Bleeding Kansas.'

Transcontinental Railroad

Proposed rail line connecting East and West; debates over its route intensified sectional rivalry.

Young America

Movement within the Democratic Party advocating for U.S. expansion abroad to distract from domestic sectional tensions.

John Brown

Radical abolitionist who led violent attacks in 'Bleeding Kansas' and the 1859 raid on Harpers Ferry; became a martyr for abolition.

Republican Party

Formed in 1854 by anti-slavery Whigs, Democrats, and Free-Soilers; opposed the expansion of slavery.

Free-Soil Ideology

Belief that slavery threatened free white labor and social mobility; central idea of the Republican Party.

Dred Scott Decision

1857 Supreme Court case declaring that African Americans were not citizens and Congress had no power to ban slavery in the territories.

Henry Clay

The 'Great Compromiser'; crafted the Compromise of 1850 to maintain sectional balance.

John C. Calhoun

Southern leader and pro-slavery advocate; defended states' rights and argued that slavery was a 'positive good.'

Stephen A. Douglas

Illinois senator; championed popular sovereignty and authored the Kansas-Nebraska Act; debated Lincoln in 1858.

Abraham Lincoln

Republican leader who opposed slavery's expansion; gained national fame in Lincoln-Douglas debates; elected president in 1860, prompting Southern secession.

Election of 1860

Four-way presidential race won by Lincoln; led to secession of Southern states and the Civil War.

Harpers Ferry

1859 raid led by John Brown to start a slave rebellion; failed but deepened North-South divisions.