Why is the USA so proud of itself and its flag?

Because of politics I'd think. Patriotism and the flag are constantly raised through political campaigns. It pits the populace against eachother. Republicans call Liberals "unpatriotic" and seem to try and prove that they are more. It also seems that Republicans have to point to this issue, as they obviously don't have much else to say, so it gets raised more.. They can't really talk about Economic policy, since they are terrible at it and seem to want to continue that streak..