How did the United States expand across the continent, and at what cost?
Explain westward expansion and Manifest Destiny, including the major acquisitions of territory, the Mexican-American War, the impact on American Indians, and how expansion intensified the conflict over slavery (Virginia 2015 History and Social Science SOL VUS.6).
A SOL-level answer on westward expansion for the VUS exam: the idea of Manifest Destiny, the major territorial acquisitions, the Mexican-American War and the lands it added, the displacement of American Indians, and how new western land reignited the fight over slavery.
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What this topic is asking
Standard VUS.6 asks how the United States expanded across the continent under the banner of Manifest Destiny, what lands it gained (including through the Mexican-American War), how expansion displaced American Indians, and, critically, how new western territory reignited the conflict over slavery. The last point connects this topic to the causes of the Civil War.
Manifest Destiny
The major acquisitions
In a remarkable burst between 1845 and 1848, the nation expanded to the Pacific:
- Texas (annexed 1845). The independent Republic of Texas joined the United States, a move Mexico resented.
- The Oregon Country (1846). A long dispute with Britain was settled by dividing the Oregon Country, giving the United States the Pacific Northwest.
- The Mexican Cession (1848). After the Mexican-American War (1846 to 1848), the Treaty of Guadalupe Hidalgo gave the United States a vast region including California and the modern Southwest. The California Gold Rush (1849) then drew a flood of settlers.
By 1848 the United States stretched from the Atlantic to the Pacific.
The cost to American Indians
Expansion meant the displacement and dispossession of American Indian peoples across the West. As settlers, miners, and railroads pushed onto native lands, American Indians were pressured, removed, and confined, a process that would intensify after the Civil War (the closing of the frontier). The triumphant story of expansion is also a story of loss for native nations.
How expansion reignited the slavery conflict
This is the most important connection for the course. Each new territory forced the question: would it be free or slave? Because new states changed the balance between free and slave states in the Senate, every acquisition became a battleground:
- The Missouri Compromise (1820) had tried to balance admissions and drew a line for slavery in the Louisiana territory.
- The Compromise of 1850 tried again after the Mexican Cession (admitting California free, but with a tougher Fugitive Slave Act).
- The Kansas-Nebraska Act (1854) let settlers decide ("popular sovereignty"), igniting violence in "Bleeding Kansas."
Expansion turned slavery from a regional fact into a national crisis, the direct road to the Civil War (the next module).
Try this
Q1. Define Manifest Destiny. [2]
- Cue. The 1840s belief that the United States was destined, even divinely entitled, to expand across the continent to the Pacific.
Q2. Explain why new western territory intensified the conflict over slavery. [2]
- Cue. Each territory raised the question of free or slave status; because new states shifted the balance in the Senate, every acquisition reignited the slavery fight.
Exam-style practice questions
Practice questions written in the style of VDOE exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
VA VUS SOL (released item style)1 marksThe belief in "Manifest Destiny" held that the United States was
(A) destined to free all enslaved people immediately.
(B) destined to expand across the continent to the Pacific Ocean.
(C) required to stay east of the Mississippi River.
(D) obligated to return all land to American Indians.
Show worked answer →
A single-select item on Manifest Destiny (VUS.6).
Correct answer: (B). Manifest Destiny was the belief that the United States was fated and even divinely entitled to expand westward across the continent to the Pacific.
A, C, and D contradict the idea. The test rewards the expand-to-the-Pacific definition and recognizing that this belief justified taking land from American Indians and Mexico.
VA VUS SOL (released item style)2 marksWestward expansion reignited a national conflict.
(a) Name one large area of territory the United States gained between 1845 and 1848. (b) Explain why new western territory intensified the conflict over slavery.
Show worked answer →
A two-part constructed response (VUS.6), 2 points (1 per part).
(a) 1 point: any valid acquisition, such as Texas (annexed 1845), the Oregon Country (1846), or the Mexican Cession (1848, including California and the Southwest).
(b) 1 point: each new territory raised the question of whether it would be a free state or a slave state, upsetting the balance in the Senate and forcing the nation to confront the future of slavery.
Markers reward an accurate acquisition and the free-state-versus-slave-state explanation.
Related dot points
- Describe the era from 1801 to 1860, including the Louisiana Purchase, the expansion of suffrage, key features of Jacksonian democracy, the Bank War, and Indian removal (Virginia 2015 History and Social Science SOL VUS.6).
A SOL-level answer on the early republic for the VUS exam: Jefferson's Louisiana Purchase, the expansion of voting rights to most white men, the key features of Jacksonian democracy, the Bank War, and the Indian Removal Act and the Trail of Tears.
- Explain the growth of sectionalism and the causes of the Civil War: the slavery debate, the failed compromises, key events (Dred Scott, Bleeding Kansas, John Brown), the election of 1860, and secession (Virginia 2015 History and Social Science SOL VUS.6, VUS.7).
A SOL-level answer on the causes of the Civil War for the VUS exam: the sectional divide between North and South over slavery and states' rights, the failed compromises, Dred Scott and Bleeding Kansas, the election of 1860, and the secession of Southern states including Virginia.
- Describe the antebellum reform movements, including abolitionism, the women's rights movement (Seneca Falls), the Second Great Awakening, temperance, and education reform (Virginia 2015 History and Social Science SOL VUS.6).
A SOL-level answer on antebellum reform for the VUS exam: the Second Great Awakening, the abolitionist movement (Douglass, Garrison, Tubman), the women's rights movement and the Seneca Falls Convention, temperance, and education reform, with their lasting influence on American society.
- Describe the settlement of the West after the Civil War, the role of the railroads and the Homestead Act, the destruction of the bison, conflicts with American Indians, and federal policies of removal and assimilation including the Dawes Act (Virginia 2015 History and Social Science SOL VUS.8).
A SOL-level answer on the settlement of the West for the VUS exam: the railroads and the Homestead Act, the role of the transcontinental railroad, the destruction of the bison, the wars and confinement of Plains Indians to reservations, and federal assimilation policy through the Dawes Act.
- Describe the establishment of the new government under Washington, the precedents he set (the cabinet, two terms, neutrality), Hamilton's financial plan, the rise of political parties, and the early Supreme Court (Marbury v. Madison, McCulloch v. Maryland) (Virginia 2015 History and Social Science SOL VUS.5, VUS.6).
A SOL-level answer on the early republic for the VUS exam: George Washington's precedents (the cabinet, the two-term tradition, neutrality), Hamilton's financial plan, the first political parties, and the landmark early Supreme Court cases Marbury v. Madison and McCulloch v. Maryland that defined federal power.
Sources & how we know this
- Standards of Learning Documents for History and Social Science, Adopted 2015 — Virginia Department of Education (2015)
- SOL Practice Items (All Subjects) — Virginia Department of Education (2024)