James Buchanan, Jr. (April 23, 1791 – June 1, 1868) was the 15th President of the United States from 1857–1861 and the last to be born in the 18th century.

To date he is the only President from the state of Pennsylvania and the only to remain a lifelong bachelor. As President he was a "doughface", a Northerner with Southern sympathies who battled with Stephen A. Douglas for the control of the Democratic Party. A popular and experienced politician when he took office, Buchanan's efforts to maintain peace between the North and the South alienated both sides. As the Southern states declared their secession in the prologue to the American Civil War, Buchanan's opinion was that secession was illegal, but that going to war to stop it was also illegal; hence he remained inactive. By the time he left office, popular opinion had turned against him and the Democratic Party had split in two. His handling of the crisis preceding the Civil War has led to his consistent ranking by historians as one of the worst Presidents in American history.

James Buchanan, Jr., was born in a log cabin at Cove Gap, near Mercersburg, Franklin County, Pennsylvania, on April 23, 1791, to James Buchanan, Sr. (1761-1833), and Elizabeth Speer (1767-1833). He was the second of eleven children, three of whom died in infancy. Buchanan had six sisters and four brothers.