22nd amendment, Psi, is (according to that site) the one that limits to 2 terms.
Prior to the passage of that amendment (whichever one it is), the standard
had been 2 terms, because that is all that George Washington served before stepping down (according to anecdote, he was afraid that serving more would turn him into a de facto monarch, and he did not want that after fighting so damned hard to get rid of the last one)... I believe someone was elected to a third term prior to FDR's legendary four consecutive terms, but it was FDR that really scared people into he amendment. Had he not died, he would have been President for sixteen years... and then people would get comfortable... they don't like change... and you have a president-for-life.
As it turns out, he was only President for 12, and died before he could be inaugurated on the fourth term (I could be mistaken, here, as I'm going from memory) ... but the spectre of a Good Ol' Boy's Club entrenching a person permanently in what has become one of the most powerful positions in the world was scary enough to pass an amendment
. Do you have any idea how difficult that is?
Ahm... /history lesson ... /hijack