Significant Westward Expansion Events

Why This Matters

Westward expansion isn't just a list of land deals and battles—it's the story of how the United States transformed from a coastal nation into a continental power, and the human costs of that transformation. You're being tested on the interconnected forces that drove this expansion: Manifest Destiny ideology, sectional tensions over slavery, economic opportunity, and federal Indian policy. Every event on this list connects to at least one of these larger themes, and the AP exam expects you to explain those connections.

The key to mastering this content is understanding that westward expansion created a feedback loop: new territory intensified the slavery debate, which shaped how new states entered the Union, which fueled more conflict. Meanwhile, Native American nations faced systematic dispossession through treaties, removal, warfare, and assimilation policies. Don't just memorize dates—know what concept each event illustrates and how events connect to each other.

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Territorial Acquisition and Expansion

The United States grew through purchase, negotiation, and conquest—each method reflecting different political circumstances and justifications for expansion.

Louisiana Purchase (1803)

• Doubled U.S. territory—approximately 828,000 square miles acquired from France for $15 million, or about 3 cents per acre
• Constitutional controversy arose as Jefferson, a strict constructionist, stretched federal power to complete the deal without explicit constitutional authority
• Strategic significance included control of the Mississippi River and the port of New Orleans, vital for western farmers' trade

Texas Annexation (1845)

• Slavery expansion debate intensified as Texas entered as a slave state, shifting the congressional balance
• Mexican territorial disputes remained unresolved, as Mexico never recognized Texas independence and considered annexation an act of war
• Manifest Destiny in action—annexation reflected the belief that American expansion was divinely ordained and inevitable

Oregon Treaty (1846)

• Diplomatic compromise established the 49th parallel as the U.S.-British border, avoiding war over the Pacific Northwest
• "Fifty-four forty or fight" rhetoric gave way to practical negotiation, as the U.S. couldn't fight both Britain and Mexico simultaneously
• Pacific access secured—the treaty gave the U.S. valuable ports and strengthened claims to continental dominance

Mexican-American War (1846-1848)

• Mexican Cession transferred California, Nevada, Utah, and parts of four other states to the U.S. through the Treaty of Guadalupe Hidalgo
• "Spot Resolutions" by Congressman Abraham Lincoln challenged President Polk's justification for war, questioning where American blood was actually shed
• Wilmot Proviso debates over banning slavery in acquired territories foreshadowed the sectional crisis of the 1850s

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Exploration and Infrastructure

Federal investment in exploration and transportation networks made settlement possible and profitable, transforming the West from abstract territory into accessible land.

Lewis and Clark Expedition (1804-1806)

• Scientific and diplomatic mission commissioned by Jefferson to map the Louisiana Purchase, document resources, and establish relations with Native nations
• Sacagawea's role as interpreter and guide demonstrated the essential contributions of Native Americans and women to western exploration
• Pacific Northwest claims strengthened through the expedition's journey to the Oregon coast, supporting later territorial negotiations

Transcontinental Railroad (completed 1869)

• Pacific Railroad Acts provided federal land grants and loans to Union Pacific and Central Pacific companies, establishing a model for government-business partnerships
• Chinese and Irish immigrant labor built the railroad under dangerous conditions, reflecting patterns of exploitation in American industrialization
• Economic transformation reduced cross-country travel from months to days, enabling rapid settlement, resource extraction, and market integration

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The Slavery Crisis and Sectional Conflict

Every territorial acquisition forced the nation to confront whether new lands would permit slavery, making westward expansion inseparable from the road to Civil War.

Missouri Compromise (1820)

• 36°30' line divided the Louisiana Purchase into future free territory (north) and slave territory (south), temporarily resolving the crisis
• Congressional balance maintained by admitting Missouri as a slave state and Maine as a free state simultaneously
• Jefferson's warning—he called the compromise a "fire bell in the night," recognizing it as a temporary fix that revealed deeper divisions

Compromise of 1850

• California admitted free without a corresponding slave state, breaking the pattern of balanced admissions
• Fugitive Slave Act required northern citizens to assist in capturing escaped slaves, inflaming abolitionist sentiment
• Popular sovereignty introduced for New Mexico and Utah territories, allowing settlers to decide slavery's status—a principle that would prove disastrous in Kansas

California Gold Rush (1848-1855)

• Population explosion brought 300,000 migrants to California by 1855, accelerating statehood and bypassing the territorial phase
• Free state admission in 1850 upset the sectional balance and contributed to the Compromise of 1850's necessity
• Diverse migration included Chinese immigrants, Latin Americans, and free Black Americans, though discriminatory laws limited their opportunities

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Native American Dispossession

Federal Indian policy evolved from removal to reservation to forced assimilation, but the consistent goal was opening Native lands to white settlement.

Indian Removal Act (1830)

• Andrew Jackson's policy authorized negotiation of removal treaties with southeastern tribes, though "negotiation" often meant coercion
• "Five Civilized Tribes" targeted included Cherokee, Chickasaw, Choctaw, Creek, and Seminole nations, despite their adoption of American institutions
• Worcester v. Georgia (1832) ruled removal unconstitutional, but Jackson reportedly ignored the Supreme Court, demonstrating executive defiance of judicial authority

Trail of Tears (1838-1839)

• Forced relocation of approximately 16,000 Cherokee resulted in an estimated 4,000 deaths from exposure, disease, and starvation
• Cherokee resistance included legal challenges and the Cherokee Phoenix newspaper campaign, demonstrating sophisticated political engagement
• "Indian Territory" destination (present-day Oklahoma) became a dumping ground for displaced eastern tribes, creating new intertribal conflicts

Battle of Little Bighorn (1876)

• Lakota and Cheyenne victory over Lieutenant Colonel George Custer's 7th Cavalry became the most famous Native American military triumph
• Sitting Bull and Crazy Horse led the resistance against U.S. violation of the 1868 Fort Laramie Treaty, which had guaranteed the Black Hills to the Sioux
• Pyrrhic victory—the battle intensified U.S. military campaigns and public support for aggressive Indian policy

Dawes Act (1887)

• Allotment policy divided communal tribal lands into individual 160-acre plots, with "surplus" land sold to white settlers
• Assimilation goal aimed to transform Native Americans into individual farmers and destroy tribal social structures
• Land loss catastrophic—Native American landholdings dropped from 138 million acres to 48 million acres by 1934

Wounded Knee Massacre (1890)

• Ghost Dance suppression motivated the army's confrontation with Lakota Sioux at Wounded Knee Creek, South Dakota
• Approximately 250-300 Lakota killed, including women and children, by the 7th Cavalry—Custer's former regiment
• End of armed resistance symbolically marked, though Native American activism continued through legal and political channels

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Settlement and the Closing Frontier

Federal land policy and the ideology of Manifest Destiny encouraged millions of Americans to migrate west, transforming the landscape and displacing Native peoples.

Homestead Act (1862)

• 160 free acres offered to any citizen (or intended citizen) who improved the land and lived on it for five years
• Wartime passage possible only after southern secession removed congressional opposition to free-soil settlement
• Limited success—only about 40% of applicants completed the requirements, and much western land was better suited for ranching than farming

War of 1812

• Native American alliances broken as British defeat ended support for Tecumseh's confederacy and removed a barrier to northwestern expansion
• National identity strengthened through the "Second War of Independence," fostering the nationalism that would fuel Manifest Destiny
• Creek War (1813-1814) during this conflict opened millions of acres in the Southeast to white settlement

Closing of the Frontier (1890)

• Census Bureau declaration that no continuous frontier line existed marked the symbolic end of westward expansion
• Frederick Jackson Turner's thesis (1893) argued the frontier had shaped American democracy and character, raising anxious questions about national identity
• New imperialism emerged as expansionist energy turned toward overseas territories in Hawaii, Cuba, and the Philippines

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Quick Reference Table

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Self-Check Questions

1. Which two events best illustrate how territorial expansion intensified the slavery debate, and what specific mechanisms (congressional balance, popular sovereignty, etc.) did each involve?

2. Compare the Indian Removal Act and the Dawes Act: How did federal Indian policy shift from removal to assimilation, and what was the impact on Native American landholdings in each case?

3. If an FRQ asked you to explain how the federal government promoted westward expansion, which three events would you choose and why?

4. What connects the Missouri Compromise (1820), the Compromise of 1850, and the Mexican-American War? How did each contribute to the coming of the Civil War?

5. Compare the Trail of Tears and Wounded Knee: What do these events reveal about the evolution of U.S.-Native American relations across the 19th century, and how did Native American resistance strategies change over time?