While Manifest Destiny and territorial expansion created conflict with foreign nations, including the Mexican-American War (1846-1848), and within the United States, it worked to unify the United States from 1830 to 1860 by strengthening the nation as a whole, creating economic opportunities for people from all different walks of life, and expanding the United States through the annexation of Texas and the acquisition of California from Mexico.
The United States became further united due to the continuous desire and procurement of new territories. In President James Polk’s 1845 Inaugural Address, he shared his opinion of the “danger to [the nation’s] safety and future peace” if Texas remained an independent state. Polk’s point of view was that the annexation of Texas in 1845 was necessary in order to avoid a conflict with Mexico. However, the United States went to war with Mexico anyway over the California territory. Economic opportunities were created in California due to the gold rush, which brought many people from many different ethnicities. California became a “seat of wealth and power,” due to the California Gold Rush (1848-1855) and its acquisition from Mexico after the Mexican-America War, as foreshadowed by an anonymous writer of the 1846 article “California and the National Interest” in the Whig journal American Review.
The author’s purpose was to highlight the territories of California, Oregon and Texas with the intention to promote Manifest Destiny and westward expansion in a published Whig journal. Whigs promoted rapid economic and industrial growth, including the expansion of territories through Manifest Destiny, by demanding government support for a more modern, market-oriented economy, suggesting high tariffs, and funding internal improvements. The term Manifest Destiny was coined by John O’Sullivan, the editor of the 1846 Democratic Review. He claimed in his article that California will “fall away from Mexico…and a population will soon be in actual occupation of [it].” In stating this, he was foreshadowing the end of the war and the forced Mexican cession of the territories of California and New Mexico to the United States in exchange of $15 million.
Despite these amalgamating events, westward expansion engendered conflict not just between the United States and Mexico, but among American citizens. William Ellery Channing, an abolitionist and pacifist, wrote a letter to Henry Clay concerning the annexation of Texas, claiming that the United States was “provoking war by cupidity, encroachment…and by efforts to propagate the curse of slavery.” His objective was to discourage the annexation of Texas in an attempt to prevent the Mexican war in years to come. His view of westward expansion contradicts with the opinion expressed in the American Review in that the anonymous writer supported the annexation of Texas. Channing felt that acquiring Texas would not only spark conflict with Mexico but would also create problems in the United States in regards to slavery.
This issue over the extension of slavery in Texas presaged Bleeding Kansas, a series of violent political confrontations involving anti-slavery Free Soilers and pro-slavery Southerners that took place in the Kansas Territory between 1854 and 1861.After President Polk was able to obtain Texas from Mexico, he set his target on the California Territory. Senator Thomas Corwin was able to see that with expanding territories came war with Mexico and debates over slavery if the United States won, which he argued in his 1847 speech to Polk. His point of view was that even if the United States won the war with Mexico and gained possession of California, there would only be more conflict in the homeland on the topic of California being admitted as a slave or free state. He questions Polk’s reasoning in the nation’s “[participation] in the [Mexican War]” if only to create a “civil conflict…over the question of slavery.”
This issue was later resolved by the Compromise of 1850, which admitted California as a free state. The Compromise was drafted by Henry Clay, a Whig, and Stephen Douglas, a Democrat. Douglas supported the political doctrine of popular sovereignty, or the principle that the state government could decide the fate of slavery in their region. Senator Charles Sumner, too, felt that westward expansion would divide the nation over the issue of slavery, arguing in Massachusetts Legislature that the Mexican-American War was “unconstitutionally commenced by the order of the President” and if the nation were to obtain the California territory it would “strengthen slave power.” President Lincoln shared the opinion in his famous spot resolutions that requested President Polk to provide Congress with the exact spot upon which blood was spilt on American soil, as Polk had claimed in 1846 when asking Congress to declare war on Mexico. Slavery was a commonly debated issue that was associated with Manifest Destiny, which eventually led to the Civil War, ultimately dividing the nation. Though westward expansion unified the United States temporarily, it only delayed the inevitable war over slavery and states’ rights.
From 1800 to 1850 territorial expansion tore the United States apart. Territorial expansion itself was not a debated issue. Spurred by the concept of Manifest Destiny, almost everyone believed that America should extend from sea to shining sea and maybe even farther. But it was the issue of the expansion of slavery into the new territories that pitted the North against the South and split our nation apart.
The first real crisis over territorial expansion took place in 1819-1821 over the admission of the state of Missouri. The proposed state of Missouri was the first (beside Louisiana itself) to be carved out of the Louisiana Purchase. It lay out of the jurisdiction of the Northwest Ordinance, which prohibited slavery in the Northwest Territories, and had a long tradition of slavery. Therefore, in 1817 Missouri applied to the Union as a slave state. The extension of slavery so far north and the threat of further expansion of slavery into all new territories of the U.S.
created havoc in Congress. In February 1819, Congressman James Tallmadge, from New York, proposed an amendment that would prohibit any new slaves to enter the state and provided that all slave children born after the date of admission would be set free at the age of twenty-five. Tallmadge's gradual emancipation proviso received almost unanimous opposition from Southern Congressmen. The amendment twice passed the North dominated House of Representatives, only to be turned down by the balanced Senate. In December 1819, Maine applied for statehood as a free state. In the end a compromise was reached where Maine would enter the Union as a free state, Missouri would enter the Union as a slave state without restrictions, but in the remaining Louisiana territory slavery would be prohibited north of 36o30' (the Mason-Dixon Line). This is now known...