James K. Polk’s first State of the Union Address, on 2 December 1845, promoted the concept that the US should encompass all of North America.
James Polk was the first president to vocalise the concept that the US should stretch ‘from sea to shining sea’.
This concept of Manifest Destiny was not Polk’s own. The first use of the term has been credited to newspaper editor John O’Sullivan. It was embraced by the Democrats, who saw white Anglo-Saxon America as a civilising Christian influence with a rightful claim to the whole continent, regardless of the long histories of the native peoples or European powers they found there.
Under Polk, Manifest Destiny was put into action with the annexation of the nominally independent Texas and the ceding from Mexico of parts of nine states. Having announced this huge increase in the size of the US, which he rather bewilderingly referred to as a ‘bloodless achievement’, his address went on to assert ‘our title to the whole Oregon Territory’, which was followed by a claim that ‘The civilized world will see in these proceedings a spirit of liberal concession on the part of the United States.’ This might have left the British a little baffled, but the aggressive stance did lead to them backing down and signing the Oregon Treaty the following year, dividing the whole territory along the 49th Parallel.
Polk ended with the battle cry of Manifest Destiny:
It is to the enterprise and perseverance of the hardy pioneers of the West, who penetrate the wilderness with their families, suffer the dangers, the privations, and hardships attending the settlement of a new country ... that we are in a great degree indebted for the rapid extension and aggrandizement of our country.
But as tensions rose between slave and non-slaving owning states over who should control these vast new lands, Polk’s nationalism was sowing some of the first seeds of the Civil War.