James K. Polk was born on November 2, 1795 in Mecklenburg County, North Carolina. He died on June 15, 1849. He moved with his family at the age of ten to Tennessee. He was a sickly youth who suffered from gallstones. Polk did not begin his formal education until 1813 at the age of 18. By 1816, he entered the University of North Carolina and graduated with honors in 1818

Often referred to as the first "dark horse" President, James K. Polk was the last of the Jacksonians to sit in the White House, and the last strong President until the Civil War.

As a young lawyer he entered politics, served in the Tennessee legislature, and became a friend of Andrew Jackson.

In the House of Representatives, Polk was a chief lieutenant of Jackson in his Bank war. He served as Speaker between 1835 and 1839, leaving to become Governor of Tennessee.

In 1844, the Democrats were having a difficult time getting the necessary 2/3 of the vote to nominate a candidate. On the 9th ballot James K. Polk who had only been considered as a Vice Presidential candidate was nominated. He was opposed by Whig candidate Henry Clay. The campaign centered around the idea of annexation of Texas which Polk supported and Clay opposed. Polk received 50% of the popular vote and won 170 out of 275 electoral votes.

James K. Polk's time in office was eventful. In 1846, he agreed to fix the boundary of the Oregon territory at the 49th parallel. Great Britain and the United States disagreed about who claimed the territory. The Oregon Treaty mean that Washington and Oregon would be a territory of the U.S. and Vancouver would belong to Great Britain. Much of Polk's time in office was taken up with the Mexican War which lasted from 1846-1848. The annexation of Texas which had taken place at the end of John Tyler's time in office hurt relations between Mexico and America. Further, the border between the two countries was still disputed. The U.S. felt that the border should be set at the Rio Grande River. When Mexico would not agree, Polk prepared for war. He ordered General Zachary Taylor to the area.

In April, 1846, Mexican troops fired on the U.S. troops in the area. Polk used this to push forward a Declaration of War against Mexico. In February, 1847, Taylor was able to defeat the Mexican army led by Santa Anna. By March, 1847, U.S. troops occupied Mexico City. Concurrently in January, 1847, Mexican troops were defeated in California.

In February, 1848, The Treaty of Guadalupe Hidalgo was signed ending the war. By this treaty, the border was fixed at the Rio Grande. By this means, the U.S. gained California and Nevada amongst other present day territories amounting to over 500,000 square miles of land. In exchange, the U.S. agreed to pay Mexico $15 million for the territory. This agreement reduced the size of Mexico to half of its former size.

After Thomas Jefferson, James K. Polk increased the size of the United States more than any other president through the acquisition of California and New Mexico as a result of the Mexican-American War. He also claimed Oregon Territory after a treaty with England. He was a key figure in Manifest Destiny. He was also an extremely effective leader during the the Mexican-American War. He is considered to be the best one-term presidents because he was responsible. In his own words:

"I prefer to supervise the whole operations of Government myself rather than entrust the public business to subordinates and this makes my duties very great."

James Polk also said: "Although in our country the Chief Magistrate must almost of necessity be chosen by a party and stand pledged to its principles and measures, yet in his official action he should not be the President of a party only, but of the whole people of the United States."

Polk, leaving office with his health undermined from hard work, died in June 1849. He had promised not to seek a second term, he kept his word, and he had the shortest life as a former President, dying on June 15, 1849, three months (103 days) after his term ended (March 4, 1849). He was also the first President or former President to die before his mother did.