Western History 158: What was Manifest Destiny?

Democrat James K. Polk (1845-1849) was the country’s  11^th President succeeding John Tyler to the White House. Polk had been a strong ally of Andrew Jackson and was a one-time Speaker of the House of Representatives. He was also a former Governor of Tennessee. Polk's presidential term was highlighted for the expansion of US territory and the ascendancy of the unwritten doctrine of Manifest Destiny (coined in 1845). Proponents of  Manifest Destiny believed that the US had a God given right to expand across North America and thus extend American social and economic values (most notably Free Enterprise) across a far broader domain.

                                                  James Polk  Source: www.history.com

It was this philosophy that would play an important role in Polk’s thinking. In 1846 a settlement was reached with Great Britain known as the Oregon Treaty. This treaty set the border between the US and British North America for territory west of the continental divide at the 49^th Parallel (with the exception of Vancouver Island which was retained by Great Britain) ending an ongoing dispute that had existed since 1818. The US formalized its acquisition of the area that would become the states of Washington and Oregon. The 49^th parallel would eventually become the border between the US and  the later nation of Canada.

In 1845 the Republic of Texas was finally annexed into the United States. It would become the Union’s 28^th state. Texas had earlier on rebelled against the centralist Mexican authority  in 1836 and after a brutal struggle that saw  heroics at the Battle of the Alamo and then a final victory at the San Jacinto had earned a de facto Independence from Mexico (outlined in the Treaty of Velasco).  Its First and Third President was Sam Houston..

An artist's impression of the spirit of Manifest Destiny    source: www.newsweek.com

Relations with Mexico however deteriorated resulting in the Mexican-American War (1846-1848).  US forces were victorious and with the signing of the Treaty of Guadalupe Hidalgo the US acquired vast amounts of territory north of the Rio Grande that would eventually become the states of California, New Mexico (roughly half of the modern day area), almost all of Arizona, Nevada, Utah and Colorado. This combined territory was collectively known as the Mexican Cession. Financial claims were settled and Mexico was forced to recognize US sovereignty over Texas. The War itself  saw the US invasion of Mexico and the capture of Mexico City by the forces of General Winfield Scott.

Territory of  Guadalupe Hidalgo source: https://www.ssc.wisc.edu/

However far from being a win for the United States the newly acquired territory would in the short term cause more domestic turmoil as it further highlighted the slavery debate by bringing to the fore the ever pressing issue of whether slavery should be extended into the newly acquired territory.

From a historical perspective Polk is seen as one of the most competent American Presidents. The territorial acquisitions did much to bolster this claim (that was given an added boost by the California Gold Rush) and he largely avoided the scandals that had dogged other Presidents. Polk adhered to his original pledge that he would only be a one-term President and  was succeeded by Zachary Taylor who was a military hero from the Mexican-American War but was not Polk’s choice for the White Office (he preferred Lewis Cass). Polk passed away soon after leaving office.