Lots of countries have similar sorts of histories I think; while I'm sure what you say is part of the equation, I think it doesn't fully explain why Americans are much more likely to support Israel than people in other countries (for instance, Australia.) I think another piece of this puzzle is the popularity of Evangelical Christianity in America, particularly Christian Zionism and the belief that the state of Israel is a necessary precondition for the return of their Messiah. That's the sort of rhetoric I was raised with anyway.