On this 11th Presidential Friday, we study President James Knox Polk. His rise to the presidency was a surprise, as he had been relatively obscure as a member of the Democratic party. His Whig party opponents even joked, "Who is James K. Polk?" Then, when he won the election against Henry Clay, Polk was considered a "dark horse" candidate.
Though Polk was initially seeking only Vice Presidency, his ambitions rose when both Democratic and Whig candidates stated their opposition to the annexation of Texas, unlike Polk. However, Andew Jackson sensed the people's urge for expansionism and urged his party to nominate an expansionist candidate, which led to Polk's name appearing on the ballot for President.
Indeed, Polk felt strongly about the US owning certain territories. He nearly went to war with the United Kingdom over control of the Oregon territory, eventually splitting it with the Brits. Additionally, he led the US to success in the Mexican-American war and therefore control of Texas. In addition, he established a treasury system lasting until 1913. For all this, Polk is sometimes referred to as the "least known consequential president."
He pledge to serve only one term and followed through, dying of cholera only three months post his presidential term. Scholars rank him favorable amongst US presidents- he consistently places between 16th and 8th best President. A strong proponent of Manifest Destiny, Polk first made the US a coast-to-coast nation. For this, he is both praised and criticized.
He was also criticized during his presidency for abolitionists when he declined to forbid slavery in the new Texas area. He did, however, wish to extend the Missouri Compromise line, above which slavery would be forbidden and below which states could decide on their own for the issue of slavery. Polk himself owned slaves his entire life, but stipulated that his slaves should be freed when his wife died (though she died in 1891, long after slaves were emancipated.)
Sources: America's Library.gov, White House.gov, Wikipedia