By the 1840s, Jacksonian Democrats and many other Americans looked west. Families had begun the long wagon trip to Oregon in 1843, and Americans in Texas had broken away from Mexico. In 1845 a New York editor, John L. O'Sullivan, gave the mood a name.
Key idea
Manifest Destiny was the belief that the United States was destined, by Providence, to spread across the continent. It drove the annexation of Texas (independent from Mexico since 1836; annexed in 1845) and the Oregon Treaty with Britain (1846), which split the Oregon Country at the 49th parallel.
Why it works
Supporters gave several reasons: land for a fast-growing population of farmers, Pacific ports for trade with Asia, and the spread of what they saw as free institutions. The belief also carried a sense that Mexicans and Native peoples should give way, an idea that historians see as central to it. Critics at the time, many Whigs among them, warned that expansion meant war and would reopen the fight over slavery in new land.
Worked example: Why did Texas wait nine years?
Texas won its independence at San Jacinto in April 1836 and asked to join the United States. Why was it not annexed until 1845?
- Texas allowed slavery, so annexing it would add a large slave state and upset the balance in Congress.
- Mexico had never recognized Texas independence and warned that annexation would mean war.
- In 1844 the Senate rejected an annexation treaty.
- After James K. Polk, who favored expansion, won the 1844 election, Congress annexed Texas by a joint resolution (March 1, 1845), which needed only simple majorities. Texas became a state on December 29, 1845.
Answer: Fear of war with Mexico and of adding a slave state; it passed by joint resolution after Polk's election.
Common mistake
Manifest Destiny was not a law or a treaty. It was a belief and a slogan. The land itself came by specific means: Texas by annexation, Oregon by treaty, and, in the next lesson, the Southwest by war and a treaty. Check: if a question asks who signed Manifest Destiny, the answer is no one.
Polk's supporters had claimed all of Oregon up to latitude 54°40′, the edge of Russian Alaska ("Fifty-four forty or fight!" became a slogan). With war against Mexico coming, Polk accepted the 49th parallel, which still forms most of the border with Canada in the West.