A lawyer and former congressman from Tennessee, James Knox Polk became a "dark horse" candidate for the Democratic Party in 1844. He narrowly defeated Whig Henry Clay in the general election and succeeded John Tyler to the presidency. The major event of his administration was the Mexican War, a controversial event which fit neatly with Polk's expansionist policies. During Polk's term the Oregon question was settled (the U.S. and Britain agreeing to divide the Pacific Northwest between them at the 49th parallel) and for the first time the territory of the United States extended to the Pacific Ocean. Polk served only one term, but is considered to have been one of the more aggressively productive men ever to hold the office. He was succeeded by a popular general from the war with Mexico, Zachary Taylor.

James Polk died only three months after leaving office... He was baptized six days before his death... President Polk laid the cornerstone of the Washington Monument... Gas lighting was installed in the White House during James Polk's administration... Polk married Sarah Childress in 1824; they had no children.