Overview
This lecture examines the westward expansion of Americans in the 1840s, focusing on the political, economic, and ideological motivations, the annexation of Texas, and the early actions of President James K. Polk.
Westward Expansion and Migration
- By 1860, 4.3 million Americans had moved west across the Mississippi, settling in regions as far as the Pacific coast.
- Migration routes included major trails to Santa Fe, Northern California, and Oregon Country.
Southern Political Interests and Slavery
- Southern states sought new western lands to grow cotton and expand slavery using enslaved labor.
- The Three-Fifths Compromise gave the South disproportionate power in Congress, but this influence waned as the North and Midwest populations grew.
- The desire to maintain Southern political power made western expansion and the annexation of new territories contentious.
Manifest Destiny
- In 1845, John O'Sullivan coined "Manifest Destiny," the belief that the U.S. had a divine mission to expand its territory and spread liberty.
- Manifest Destiny fueled aggressive U.S. foreign policy and justified territorial expansion, including actions toward Mexico.
Annexation of Texas
- After winning independence, Texas struggled with debt, lack of infrastructure, and ongoing Mexican claims.
- Southerners supported Texas annexation to expand slavery, while Northerners opposed it to limit slave-state power.
- A Senate treaty to annex Texas failed in 1843 due to Northern resistance, fearing expansion of the "slave power."
Election of 1844 and Presidential Actions
- Both major parties initially tried to avoid the Texas issue in the 1844 election.
- Southern Democrats replaced Martin Van Buren with James K. Polk, who championed Texas annexation and expansion.
- Polk won a narrow victory over Henry Clay, largely because of shifts in New York votes to a third party.
- President John Tyler secured Texas annexation via Congressional joint resolution before Polk took office.
Impact and Tensions with Mexico
- Official annexation of Texas in 1845 allowed slavery and provoked tensions with Mexico, which never recognized Texas independence.
- Mexico considered U.S. annexation of Texas as theft and a potential cause for war.
Polk's Expansion Goals
- President Polk prioritized adding Oregon, California, and New Mexico to the U.S.
- The Oregon border dispute with Britain was settled in 1846 via the Oregon Treaty along the 49th parallel.
- Acquiring California and New Mexico likely meant war with Mexico.
Key Terms & Definitions
- Manifest Destiny — the belief that the U.S. was destined to expand across the continent, spreading its values and institutions.
- Three-Fifths Compromise — counted three-fifths of enslaved people for Congressional representation, boosting Southern political power.
- Annexation — the formal addition of territory to a nation.
- Oregon Treaty (1846) — agreement with Britain setting the U.S.-Canada border at the 49th parallel in the Oregon Country.
Action Items / Next Steps
- Review the effects of Manifest Destiny and the annexation of Texas on U.S.-Mexico relations.
- Prepare for next class discussion on the outbreak of the Mexican-American War.