“[I]n 1845, [journalist John] O’Sullivan wrote another essay titled Annexation in the Democratic Review, in which he first used the phrase manifest destiny. In this article he urged the U.S. to annex the Republic of Texas, not only because Texas desired this, but because it was “our manifest destiny to overspread the continent allotted by Providence for the free development of our yearly multiplying millions”. Overcoming Whig opposition, Democrats annexed Texas in 1845. O’Sullivan’s first usage of the phrase “manifest destiny” attracted little attention.
O’Sullivan’s second use of the phrase became extremely influential. On December 27, 1845, in his newspaper the New York Morning News, O’Sullivan addressed the ongoing boundary dispute with Britain. O’Sullivan argued that the United States had the right to claim “the whole of Oregon”:
And that claim is by the right of our manifest destiny to overspread and to possess the whole of the continent which Providence has given us for the development of the great experiment of liberty and federated self-government entrusted to us.