James K. Polk (November 2, 1795 - June 15, 1849) was the eleventh President of the United States, serving from March 4, 1845 to March 3, 1849. Polk was born in Mecklenburg County, North Carolina but mostly lived in and represented the state of Tennessee. A Democrat, Polk served as Speaker of the House (1835-1839) and governor of Tennessee (1839-1841) prior to becoming president. He is noted for his success in winning a war with Mexico and adding vast new territories. He lowered the tariff and established a treasury system that lasted until 1913. A "dark horse" in 1844, he fulfilled his promise to serve only one term, and died three months after his term ended.
His term is most notable for the largest expansion of the nation's boundaries since the Louisiana Purchase, through the negotiated establishment of the Oregon Territory and the purchase of 1.2 million square miles (3.1 million square kilometers) through the Treaty of Guadalupe Hidalgo that ended the Mexican-American War. The expansionism, however, opened a furious debate over slavery in the new territories that was resolved by the Compromise of 1850. He signed the Walker Tariff that brought an era of near free trade to the country until 1861. He oversaw the opening of the U.S. Naval Academy and the Washington Monument, and the issuance of the first postage stamps in the United States. Scholars rank him about #10-12 on the list of greatest presidents for his ability to set an agenda and achieve all of it.