James K. Polk — 11th President (1845–1849)

**James K. Polk** is the most effective one-term president in American history. He set four goals, achieved all four, and went home. He acquired California and the Southwest from Mexico, settled the Oregon boundary with Britain, reduced the tariff, and established an independent treasury. Then he declined to run for reelection because he said he wouldn't, and he died three months after leaving office — literally worked himself to death.