Manifest Destiny

By the end of this lesson, students will be able to:

• Account for the religious, racial, demographic, and political arguments that John L. O'Sullivan welded into the doctrine of Manifest Destiny in his 1845 magazine essay.
• Trace the diplomatic chain that connected the election of 1844, the joint resolution annexing Texas in 1845, and the Oregon Treaty of 1846, including the campaign slogan "Fifty-four forty or fight" and Polk's eventual settlement at the forty-ninth parallel.
• Account for the demographic reach of westward migration, including the Oregon Trail, the California Trail, and the Latter-day Saints' migration to the Great Basin under Brigham Young in 1846 and 1847.
• Account for how the federal pursuit of continental expansion produced violent conflict with Mexican and Native nations, including the Plains and Western tribes whose homelands were now bisected by the new United States boundary, and locate the long shadow of the Indian Removal Act and the Trail of Tears in the antebellum dispossession of those nations (KC-5.1.I.B).
• Use Skill 1.B (Explanation of Historical Concepts) to explain how the rhetoric of Manifest Destiny was contested by William Lloyd Garrison, Henry David Thoreau, and Whigs in Congress, and how those critiques previewed the sectional argument that would dominate the rest of Period 5.

Manifest Destiny was an argument before it was a policy. By the early 1840s, three trains of thought were already moving in tandem in American public life: a popular religious sense that Providence had arranged the continent for the United States to settle, a demographic argument that a fast-growing population needed new agricultural land, and a racial and political claim that what speakers of the day called Anglo-Saxon institutions of self-government were inherently superior to those of the peoples already living west of the Mississippi. John L. O'Sullivan, the Democratic editor of the United States Magazine and Democratic Review, fused those threads into a single phrase in the summer of 1845 to defend the annexation of Texas against critics who warned it would mean war with Mexico. The phrase outran the essay almost immediately. By the end of 1846, Manifest Destiny was the rhetorical scaffolding for federal policy across the West (KC-5.1.I.B).

Texas was the first test of the doctrine. The Republic of Texas had won independence from Mexico in 1836 and operated for nearly a decade as a slaveholding republic, repeatedly petitioning Washington for admission to the Union. Annexation had stalled because admitting Texas would add a large new slave state and risked war with a Mexican government that had never recognized Texan independence. The 1844 election broke the stalemate. James K. Polk ran as the Democratic candidate on a maximalist expansionist platform that demanded the "reannexation of Texas" and the "reoccupation of Oregon" all the way to latitude 54 degrees and 40 minutes north, the southern boundary of Russian Alaska. The Whig nominee Henry Clay opposed annexation and lost narrowly. Outgoing President John Tyler treated the result as a mandate, secured congressional passage of a joint resolution in February 1845, and Texas entered the Union in December of the same year as the twenty-eighth state. The joint resolution required only simple majorities in both houses, sidestepping the two-thirds Senate margin a treaty would have demanded (KC-5.1.I.B).

Oregon was the second test. The Oregon Country, the vast region between the forty-second parallel and latitude fifty-four forty, had been jointly occupied by the United States and Britain since the Convention of 1818. American settlers, drawn by reports of fertile valleys and a temperate climate, traveled the Oregon Trail in growing numbers through the early 1840s. The 1844 Democratic slogan "Fifty-four forty or fight" demanded the entire region. Once in office, Polk discovered the limits of his own rhetoric. War with Mexico was already approaching, the United States Navy was outclassed by the Royal Navy, and the cabinet preferred a negotiated boundary. The Oregon Treaty of June 1846, signed in Washington by Secretary of State James Buchanan and the British minister Richard Pakenham, set the boundary at the forty-ninth parallel and gave the United States present-day Oregon, Washington, and Idaho. The slogan survived the compromise. The United States had reached the Pacific by treaty, and the diplomatic energy now shifted south.

Migration was the doctrine in motion. By the mid-1840s, the overland trails had become the largest continental migration in American history to that point. Roughly fifty thousand emigrants reached Oregon between 1843 and 1860 along the trail that began at Independence, Missouri, ran along the Platte River, crossed the Continental Divide at South Pass, and descended the Snake and Columbia rivers. The California Trail branched off in southern Idaho and crossed the Forty Mile Desert to Sutter's Fort. The discovery of gold at Sutter's Mill in January 1848, weeks before the Treaty of Guadalupe Hidalgo formalized the cession of California, set off the largest single-year migration in American history: roughly ninety thousand forty-niners reached California in 1849, and the territorial population exceeded two hundred thousand non-Native residents within four years (KC-5.1.I.A).

The Latter-day Saints' migration to the Great Basin was the period's most striking religious migration. After the murder of the founder Joseph Smith at Carthage, Illinois in 1844 and a decade of expulsions from Ohio, Missouri, and Illinois, Brigham Young led the main body of the Church of Jesus Christ of Latter-day Saints west from Nauvoo beginning in February 1846. The vanguard company reached the Salt Lake Valley in July 1847; by the early 1850s roughly seventy thousand members of the Church had gathered into the basin, founding Salt Lake City and a network of agricultural settlements stretching from southern Idaho into Arizona. The Utah migration is also a complication of the standard Manifest Destiny story: the Latter-day Saints crossed federal territory to escape American religious persecution, only to find themselves inside the Mexican Cession when the Treaty of Guadalupe Hidalgo redrew the boundary in February 1848 (KC-5.1.I.A).

Expansion was not movement into empty land. The territories the United States acquired and the routes its settlers traveled were the homelands of dozens of Native nations and of Mexican citizens whose families had lived in the Southwest for generations. The federal Indian Removal Act of 1830 had already forced the Cherokee, Creek, Choctaw, Chickasaw, and Seminole nations west of the Mississippi during the 1830s, a forced migration the Cherokee remember as the Trail of Tears in which roughly four thousand Cherokee died of exposure, hunger, and disease. Period 5 expansion compounded that displacement. The Plains, the Great Basin, and the Southwest were governed in fact by the Comanche, the Lakota, the Cheyenne, the Arapaho, the Kiowa, the Ute, the Paiute, the Shoshone, the Navajo, and the Apache, peoples whose territorial reach the new continental boundary now bisected. Mexican Americans in California, New Mexico, and the Texas border lands lost land, citizenship protections promised in the Treaty of Guadalupe Hidalgo, and, in practice, the legal standing the treaty had guaranteed (KC-5.1.I.B).

Manifest Destiny was also contested at home from the moment it was named. William Lloyd Garrison wrote in The Liberator that the war with Mexico was a war for slaveholders and that any new territory acquired from Mexico would be sought as ground for the further extension of slave labor. The transcendentalist Henry David Thoreau refused to pay the Massachusetts poll tax, was briefly jailed in Concord in July 1846, and published the essay "Resistance to Civil Government" in 1849 (later titled "Civil Disobedience"), which argued that a citizen of conscience was obligated to withhold cooperation from a state engaged in unjust war and slaveholding. Whigs in Congress, including the freshman Illinois representative Abraham Lincoln, challenged the constitutional and factual basis of Polk's war message in the 1847 Spot Resolutions, which demanded that the president identify the precise spot where American blood had been shed on American soil. Northern editors and pulpits called the war an aggressive grab for cotton land, and the antiwar position would be a Whig and free-soil rallying point through the late 1840s (KC-5.1.I.E).

The doctrine also looked outward. The same expansionist enthusiasm produced Commodore Matthew C. Perry's expedition to Japan in 1853 and 1854, which forced the Tokugawa shogunate to sign the Treaty of Kanagawa and opened two Japanese ports to American trade, and the federal interest in transpacific commerce that would shape the politics of California and the Pacific Northwest for the rest of the century (KC-5.1.I.E). Manifest Destiny was never confined to the continent it named. Its political logic, the claim that American institutions were destined to spread, would resurface in the filibuster expeditions to Cuba and Nicaragua during the 1850s and would echo, transformed, in the imperial debates of the 1890s.

The lesson closes by setting up the next two units of analysis. Topic 5.3 carries the story directly into the Mexican-American War, where the doctrine became a shooting war that the Treaty of Guadalupe Hidalgo would settle in February 1848 with the cession of more than 525,000 square miles. Topic 5.4 picks up the constitutional consequence: every acre Mexico ceded raised the question of whether the territory would be slave or free, the Wilmot Proviso made that question unavoidable, and the Compromise of 1850 was the country's last attempt to set the question aside without settling it.

Five sources track Topic 5.2 from the moment the slogan was named through the diplomatic settlements of 1845 and 1846 and out onto the trails. Three are at the Library of Congress, two are at the Avalon Project at Yale Law School.

1. (Causation) Identify the three arguments O'Sullivan welded into the doctrine of Manifest Destiny in his 1845 essay. Which of the three was most consequential for federal policy between 1845 and 1848, and on what evidence?
2. (Comparison) Compare the Texas annexation of 1845 with the Oregon Treaty of 1846. One was settled by a joint resolution that risked war with Mexico, the other by a negotiated boundary that backed down from a maximalist campaign slogan. What accounts for the different outcomes, and what does the comparison reveal about the limits of Manifest Destiny in 1846?
3. (Causation) Account for how westward migration along the Oregon and California Trails and the Latter-day Saints' migration to the Great Basin reshaped the demographic and political map of the territories the United States was acquiring. Which migration produced the most significant political consequence, and why?
4. (Continuity and Change) Trace the line of dispossession that runs from the Indian Removal Act of 1830, through the Cherokee Trail of Tears, into the displacement of Plains, Great Basin, and Southwest Native nations during Period 5. Identify one continuity and one significant shift between the antebellum removals and the Period 5 expansion.
5. (Causation) Account for the antebellum critics of Manifest Destiny: William Lloyd Garrison, Henry David Thoreau, and Whigs in Congress such as Abraham Lincoln. How did each frame the argument against expansion, and which critique would prove most durable in the sectional debates that followed?

Draft alignment — pending educator review. AP USH codes correspond to the official College Board Course and Exam Description (Effective Fall 2023, Version 1). Statements below are paraphrased in the CountryReports voice; refer to the College Board's published CED for verbatim wording.