Ok everyone, I'm feeling adventerous so I'm starting the debate: who was the best and worst President of American history?
Rules: State President(s) / Years of Term(s) followed by a description of WHY he was good/bad. Your reasoning must be from as much fact as possible, as this is more objective than subjective. I'll go first.

Best President Ever: James K. Polk. Polk was simply amazing, due to the fact that he expanded America's borders and kicked a lot of butt on the way. Not to mention, he lowered the tariffs (a popular move), as well got some railroadage from the east to the west (ala Gadsen Purchase). He managed to make as little people angry at the time and boosted American Nationalism.

Worst President Ever: James Buchanan. Wow, this guy is the epitome of loserdome. Not only did he let S Carolina secede with no militaristic action, he basically sat in office doing only what congress told him to. He literally did nothing important in office.