Territorial Expansion, Sectional Conflict, and Pacific Trade (1840s–1850s)

Vocabulary flashcards covering 1840s–1850s American territorial expansion, key political leaders, economic developments, and Pacific diplomacy.

Manifest Destiny

The widespread American belief, coined by journalist John L. O’Sullivan in 1845, that the United States was divinely ordained by God to expand its democratic and capitalistic institutions across the entire North American continent.

Texas Annexation

The 1845 incorporation of the Republic of Texas into the United States as the 28th state, achieved via a joint resolution of Congress under President John Tyler.

Fifty-four Forty or Fight

The popular Democratic campaign slogan used in the 1844 presidential election by expansionists demanding that the United States claim the entirety of the Oregon Territory up to the parallel 54°40′ north.

Ostend Manifesto

A confidential 1854 memorandum drafted by three American diplomats in Ostend, Belgium, urging the United States to purchase Cuba from Spain for $120 million or seize it by force if Spain refused.

Mexican-American War

A conflict fought between the United States and Mexico from 1846 to 1848, instigated by President Polk deploying U.S. troops into a disputed border region between the Nueces River and the Rio Grande.

Treaty of Guadalupe Hidalgo

The 1848 treaty negotiated by Nicholas Trist that officially ended the Mexican-American War, establishing the Rio Grande as the southern border of Texas and ceding the Mexican Cession to the U.S. for $15 million.

Mexican Cession

The vast Southwestern territory—including modern California, Nevada, Utah, and parts of Arizona, New Mexico, Colorado, and Wyoming—ceded by Mexico to the U.S. in 1848, increasing the size of the U.S. by over 20%.

Gadsden Purchase

An 1853 agreement under President Franklin Pierce arranged by James Gadsden, purchasing a strip of land in southern Arizona and New Mexico from Mexico for $10 million to facilitate a southern transcontinental railroad route.

John Tyler

The 10th President of the United States (1841–1845) who assumed office after William Henry Harrison died; he broke with the Whig Party by vetoing its policies and initiated the annexation of Texas.

James K. Polk

The 11th President of the United States (1845–1849), a Democrat 'dark horse' candidate who lowered the tariff, re-established an independent treasury, acquired Oregon to the 49th parallel, and acquired California and New Mexico.

Franklin Pierce

The 14th President of the United States (1853–1857), a Northern Democrat with Southern sympathies ('Doughface') whose administration pursued the Ostend Manifesto, Gadsden Purchase, and the 1854 Kansas-Nebraska Act.

Zachary Taylor

A Mexican-American War hero elected as the 12th President of the United States (1849–1850) on the Whig ticket; he took a firm nationalist stance against the expansion of slavery by urging California to apply directly for free statehood.

John C. Fremont

An American military officer and explorer known as 'The Pathfinder' who aided the Bear Flag Revolt (1846) in California and served as the first Republican presidential candidate in 1856.

Railroads (Context of the 1840s–1850s)

Steam-powered transportation networks that expanded rapidly in the mid-19th century, serving as America's first giant commercial enterprise and economically linking the Northeast and Midwest while isolating the South.

Panic of 1857

A sharp financial crash and economic depression caused by domestic railroad over-expansion, falling European demand for American farm goods, and land speculation bank failures that left the Southern cotton economy largely unharmed.

Gold Rush

The mass migration of over 300,000 'Forty-Niners' to California following the discovery of gold at Sutter’s Mill in 1848, which rapidly urbanized the region and spurred California's 1849 free statehood application.

Farming/Urban Frontier

The mid-19th-century permanent settlement of pioneer families on western farmlands—aided by Cyrus McCormick’s mechanical reaper—alongside the rapid rise of supply hubs like San Francisco and Denver.

Federal Land Grants

Federal policies transferring large tracts of public land to state governments and private corporations, beginning prominently with the Illinois Central Railroad in 1850, to subsidize major transportation infrastructure.

Matthew C. Perry

The U.S. Navy Commodore dispatched by President Millard Fillmore in 1853 with a fleet of steam warships to Japan, using gunboat diplomacy to force Japan to abandon its two-century-old isolationist policy.

Kanagawa Treaty

An 1854 treaty signed between the United States and the Tokugawa Shogunate of Japan that opened two Japanese ports to American trade ships, protected shipwrecked sailors, and permitted a U.S. consulate.