James K. Polk & Manifest Destiny

Instructor: Logan Thomas

Logan has taught college courses and has a master's degree in history.

In this lesson, we'll learn how incoming President of the United States James Polk used an expansionist fervor in the 1840s to justify spreading the country west by any means necessary. Polk risked war with Great Britain and Mexico to alter the course of the United States.

The Call for Westward Expansion

In the 1800s, a great debate was brewing in the United States regarding the future growth of in the relatively young country. Should the U.S. expand? How would it do so? When James K. Polk was elected president in 1844, he believed voters chose him to lead the continued expansion of the United States into lands currently owned by other countries.

President James K. Polk
President James Polk

By the 1830s, the North American map showed Mexico, Great Britain, and the United States holding different regions of the continent. In the north, Great Britain claimed the rights to modern day Canada and Oregon. In the southwest, stretching from California to Texas, the recently independent Mexico held its Northern Territories. From the Atlantic Ocean to the borders of the Northern Territories of Mexico, the United States was comprised of more than two dozen states, with roughly half being slave-holding states.

Political Map of North America
US Map 1840

The United States felt positioned and destined for growth. Democrats, whose power came primarily from southern slave states, wanted to see the U.S. expand into the fertile western lands and bring the institution of slavery with them. While some northerners saw the possibility of commercial prospects in the west, others feared the expansion of slavery would doom the United States to an eternal future as a slave nation.

There was plenty of debate centered around how and where the United States would grow, but by the early 1840s, the focus for expansion began to center on what would become present-day Texas and Oregon. The call for expansion into these territories was led by the War Hawks, a group of young and aggressive U.S. politicians who hailed primarily from slaveholding states in the south and west. This ambitious group wanted to gain Mexico's Northern Territories and Britain's Oregon Territory by any means necessary.

Manifest Destiny

War seemed to be a favorable means to an end for these politicians, however, the country couldn't really start a conflict without a justifiable reason. In the 1840s, an editor and writer named John L. O'Sullivan provided the American people with the needed justification for expansion. He wrote that the United States had the God-given right and duty to occupy the land stretching to the Pacific Ocean - a concept also known as Manifest Destiny.

A painting from 1872 symbolizing the belief of Manifest Destiny
Manifest Destiny

To understand Manifest Destiny, it helps to be familiar with the general views of the American public during the early 1800s. Many white U.S. citizens believed they could profit from the acquisition of these western territories, and they justified taking these lands by racial and religious reasoning. Many white people in the United States saw Native Americans and Mexicans as inferior races, unworthy of the land they owned in the West. Others believed expansion would bring the Christian religion and a better way of life to the 'uncivilized' people living there.

A Presidential Promise

The 1844 U.S. presidential election revolved around the expansionist issue. Whig candidate Henry Clay, who feared talk of expansion would lead to war with Great Britain and Mexico, ran against Democrat James K. Polk, an expansionist, slaveholder and cotton planter. The American people elected Polk by nearly 50 percent of the popular vote and 170 electoral votes. Polk took his win as a mandate for U.S. expansion, which he promised to do once he took office.

The election results convinced the current president, John Tyler to move toward expansion in his remaining time in office. Despite the controversy over adding the large slave state to the Union, Tyler moved to annex Texas into the United States. The people of Texas, consisting primarily of immigrants from the United States, had recently fought a successful revolution to break off Mexican control and desired annexation. However, Mexico had never officially recognized Texas' independence and immediately broke off relations with the U.S. The two countries were on the brink of war by the time Polk took office.

Mr. Polk's War

Even though the new President Polk sought diplomatic ways to secure the British territory of Oregon for U.S. expansion, he charged forward into worsening relations with the Mexican government without concern for the consequences. When Mexico refused to sell their Northern Territories to the United States, Polk decided a quick war was necessary to convince Mexico to sell. He used the concept of Manifest Destiny and racist attitudes toward Mexican people as a rationale to bring the American public on board.

U.S. Cavalry attacks Mexican Troops during the U.S.-Mexican War
USMexican War

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