GerryM wrote: "Garfield was almost certainly the most intelligent man every to become President of the United States." A minority view, I think; mostly, I see people giving Jefferson that honor.

Motly, I see people who don't know who Garfield was. :-p

Jefferson is the other serious candidate, but it depends on your definition of intelligence. Since most people conflate IQ scores with intelligence (a false conflation, but it's what people do), I am using that definition.

Jefferson was more of a designer; Garfield more of an abstract thinker. If you want someone who got things done, Jefferson wins. But Garfield is the only President who created an independent proof of the Pythagorean Theorem, and he was very likely the best linguist among Presidents. He wasn't the only college president among Presidents (Wilson was one, e.g.), but he was the one who got there on merits. Contemporaries said that he was the only President who could have performed the duties of every cabinet secretary in the cabinet.

If you needed someone to get something built, Jefferson was your man. But Garfield's skills were almost tailor-made for IQ tests. So if you say that IQ tests measure intelligence (and, I repeat, I don't, but most people do), then Garfield was almost certainly the most intelligent.