Do some reading on him.  He did a TON of amazing stuff as president and he only served one term.  He deserves more attention in the pantheon of history.

Some highlights:
+ He ended the Mexican-American war, then paid the Mexicans for the land that we claimed in the Mexican-American War with the Treaty of Guadalupe Hidalgo.  This included California, Nevada, Utah, Arizona, and parts of Colorado, New Mexico, and Wyoming.
+ He also settled our claim to the Oregon Territory with the British, which added Oregon, Washington, Idaho, and portions of Montana and Wyoming to the United States.
+ He signed the Walker Tariff, which basically made free trade between states possible - without it, the North would have never won the Civil War because they would have been mired in interstate commerce rules.
+ He established the Smithsonian, the Naval Academy, and the Washington Monument.
+ He oversaw the founding of the U.S. Postal Service and oversaw the issuing of the first stamps.
+ He established an independent treasury which guided U.S. monetary policy for the next hundred years (until the establishment of the Federal Reserve).

All in four years, people.  Polk was one heck of a good president.