Manifest Destiny and President James Polk

Manifest Destiny and President James Polk

The area of the United States is about 3.8 million square miles. The country increased its size through several historical events:

  • 1783 Treaty Ending the Revolutionary War (~890,000 square miles)

  • 1803 Louisiana Purchase (President Jefferson ~820,000 square miles)

  • 1845 Texas Annexation (Presidents Tyler and Polk - ~390,000 square miles)

  • 1846 Oregon Treaty (President Polk - ~285,000 square miles)

  • 1848 Mexican Cession (President Polk - ~530,000 square miles)

  • 1867 Alaska Purchase (President Johnson - ~585,000 square miles)

Three of those events occurred under President James Polk, totaling over 1.1 million square miles.


Polk was a protégé of fellow Tennessean President Andrew Jackson. He served in the House of Representatives and as governor of Tennessee. In 1844, Martin Van Buren was the front-runner to receive the Democratic Presidential nomination, but after coming out against the annexation of Texas he was unable to obtain the then needed two-thirds majority vote at the Democratic convention. On the ninth ballot, Polk, a dark horse candidate was selected. He defeated Senator Henry Clay, who also opposed the Texas annexation, in one of the closest elections in U.S. history.

Oregon Territory

The Oregon Territory was a peaceful acquisition. Originally four different countries had claims over this Territory – Spain, Russia, Great Britain and the United States.  Spain gave up its rights in 1819 as part of the treaty ceding Florida to the United States. Russia gave up its rights in the 1820’s setting the southern limit of its territory at what is today the current border of Alaska and British Columbia.

In 1818 the United States and Great Britain agreed to a 10-year period of joint occupation while attempting to negotiate a border agreement.  Talks during the 1820’s did not yield a settlement, so the parties extended the joint occupation agreement with a one-year notice if either party wanted to leave the agreement. The United States proposed extending the 49th parallel Canadian border line from the Rockies to the Pacific.  However, the British wanted the border to go south along the Columbia river in the current state of Washington.

The Democratic Party platform of 1844 balanced out the addition of Texas as a slave state with Oregon as a free state. Polk started negotiations with Great Britain over the border and provided the one-year notice of withdrawal from the joint occupation treaty. Britain responded by sending their navy to the Pacific.  Polk was facing a potential war with Mexico and did not want two simultaneous wars. Ultimately the parties agreed to extend the 49th parallel line, with a jog south to keep Vancouver Island under British control. 

Mexican American War

The annexation of Texas was approved at the end of President Tyler’s term and finalized in December 1845 under Polk. But the border with Mexico was disputed. The United States felt it was the Rio Grande river as agreed to by Mexico in 1836 when Texas won its independence. Mexico felt the boundary was at the Nueces River near today’s San Antonio.

Polk was a believer in ‘Manifest Destiny’ and wanted to expand the country to the Pacific Coast. Negotiations to purchase California from Mexico, and to extend the border to the Rio Grande, were unsuccessful. In 1846 Polk sent a military force to the Rio Grande River to establish U.S. control. The Mexican army attacked the American force north of Rio Grande. Subsequently, Congress declared war on Mexico in May 1846. U.S. Grant, who fought in the war, later wrote that sending forces to the border was a purposeful provocation by Polk, to start a war: “We were sent to provoke a fight, but it was essential that Mexico should commence it.”

After the United States won the war, the 1948 treaty of Treaty of Guadalupe Hidalgo granted the Southwest to the United States, including the modern states of California, Nevada, New Mexico and Arizona. The United States paid Mexico $15 million for the land, and paid another $3 million in Mexican debts. On a cost per square mile basis, this was almost twice the cost of the Louisiana Territory.

Slavery divided opinion on the war. Southerners tended to support it, wanting to expand slavery. Some Northerners opposed it, wanting to prevent any slavery expansion. Abraham Lincoln, in Congress at the time, came out against the war. He said the incident at the Rio Grande was over disputed territory, not American soil. He demanded that Polk reveal the exact ‘spot’ where the initial blood had been spilled, becoming known as ‘spotty Lincoln’.Lincoln, in a letter to his law partner further expressed his concerns about the war - “Allow the President to invade a neighboring nation, whenever he shall deem it necessary to repel an invasion…and you allow him to make war at pleasure”.  

Post-Presidency of James Polk

When Polk ran for President in 1844, he promised to serve only one term. He kept his promise. Three months after his Presidency ended, Polk died, possibly of cholera. His wife lived another 42 years and wore black for all those years. Polk owned slaves and freed them in his will upon his wife’s death. It became a moot point as the slaves were freed by the end of the Civil war, 16 years after Polk’s death, 25 years before his wife died.

Polk’s main legacy is the transformation of the United States into a country that spanned from ‘sea-to-sea’.