Manifest Destiny & Mexican-American War: Key Terms & Significance

Manifest Destiny

The 19th-century belief that the United States was destined by God to expand its dominion across the North American continent.

Great American Desert

Term for the arid Great Plains used by early settlers to describe land west of the Mississippi.

Mountain Men

Frontier fur trappers and traders who explored western territories.

Far West

Region beyond the Mississippi River encompassing the Rockies and Pacific coast territories.

Overland Trails

Wagon routes (Oregon, California, Santa Fe) that carried settlers westward.

Boomtown

Expansion following gold (CA 1848) and silver (NV 1859) discoveries.

Mining Frontier / Gold Rush / Silver Rush

Catalyzed western urban growth and statehood (e.g., California 1850); reflected desire for natural resources.

Farming Frontier

Agricultural settlement of the Great Plains and West using new technology (steel plow, windmills).

Urban Frontier

Growth of new western cities like San Francisco and Denver.

John Tyler

10th President who initiated annexation of Texas.

Executive-led expansion

Set precedent for executive-led expansion prior to Polk's election; foreshadowed sectional crisis.

U.S. expansionist diplomacy

Reflected U.S. expansionist diplomacy avoided war while fulfilling part of Manifest Destiny.

1846 treaty

Dispute with Britain over Pacific Northwest boundary settled by 1846 treaty at 49° parallel.

Oregon Territory

Fifty-Four Forty or Fight!

James K. Polk

Personified Manifest Destiny politics; achieved most major territorial goals; precipitated Mexican-American War.

11th President

11th President (1845-1849), ardent expansionist advocating Texas, Oregon, and California annexations.

Texas

Former Mexican province annexed by the U.S. in 1845, leading to conflict with Mexico.

Key cause of Mexican-American War

Reignited sectional tensions over slavery expansion.

Stephen Austin

His colony's growth heightened cultural and political friction leading to Texas Revolution.

Antonio López de Santa Anna

Mexican general and dictator who fought Texas independence and U.S. invasion.

Sam Houston

Embodied independence movement fueling annexation debate; linked to war and new lands.

Alamo

Became symbol of American resistance and martyrdom; fueled expansionist nationalism.

1836 battle

1836 battle where Texas rebels were defeated by Santa Anna's forces.

Webster-Ashburton Treaty (1842)

Agreement between U.S. and Britain settling Maine-Canada border disputes.

U.S. global integration goals

Reflected U.S. global integration goals; underpinned growth of trade networks linking U.S. markets with Asia and Europe.

Foreign Commerce

Expanded American presence in Asia early step in global economic reach and cultural exchange.

Matthew C. Perry / Kanagawa Treaty (1854)

U.S. naval officer whose expedition opened Japan to trade through Treaty of Kanagawa.

Mexican-American War (1846-1848)

The war fulfilled Manifest Destiny by extending U.S. territory to the Pacific, but reignited sectional conflict over slavery in the new lands.

California

Western territory occupied by Mexico, claimed by U.S. settlers during the war and annexed after 1848.

Nueces River

River in Texas historically recognized by Mexico as the northern border of its territory.

Rio Grande

River claimed by the United States as Texas's southern boundary.

Zachary Taylor

U.S. general who led troops across the Rio Grande and won key battles at Palo Alto and Buena Vista.

Stephen Kearny

U.S. general who captured New Mexico and helped secure California during the war.

John C. Frémont

Explorer and leader of American settlers in California who declared independence as the Bear Flag Republic.

Bear Flag Republic (1846)

Short-lived republic established by American settlers in California before U.S. annexation.

Winfield Scott

U.S. general who led the final campaign from Veracruz to Mexico City (1847).

Treaty of Guadalupe Hidalgo (1848)

Treaty ending the Mexican-American War; Mexico recognized the Rio Grande as Texas's border and ceded vast territories.

Mexican Cession

Land ceded by Mexico to the U.S. (present-day CA, NV, UT, AZ, NM, and parts of CO/WY).

Wilmot Proviso (1846)

Proposal to ban slavery in all territory gained from Mexico; failed to pass but intensified sectional tension.

Mountain Men (revisited)

Fur trappers and explorers who helped map western trails used during wartime and migration.