James K. Polk, (born Nov. 2, 1795, Mecklenburg county, N.C., U.S.—died June 15, 1849, Nashville, Tenn.), 11th president of the U.S. (1845–49). He was a friend and supporter of Andrew Jackson, who helped Polk win election to the U.S. House of Representatives in 1825. He left the House in 1839 to become governor of Tennessee. At the deadlocked 1844 Democratic Party convention Polk was nominated as the compromise candidate; he is considered the first dark-horse presidential candidate. A proponent of western expansion, he openly laid claim to the whole territory that extended as far north as latitude 54° 40′ with the slogan “Fifty-four Forty or Fight” (see Oregon Question). Elected at the age of 49, the youngest president to that time, he successfully concluded the Oregon border dispute with Britain (1846) and secured passage of the Walker Tariff Act (1846), which lowered import duties and helped foreign trade. He led the prosecution of the Mexican War, which resulted in large territorial gains but reopened debate over the extension of slavery. His administration also established the Department of the Interior, the U.S. Naval Academy, and the Smithsonian Institution; oversaw revision of the treasury system; and proclaimed the validity of the Monroe Doctrine. Though an efficient and competent president and deft in his handling of Congress, he was exhausted by his efforts and did not seek reelection; he died three months after leaving office.
