tell me if im wrong, but isnt the sense of patriotism most obvious in Asian countries. I think its got to do with the fact that they r some of the oldest nations, and have all had a patch of terrible history that followed a even more glorious past, that they r all now struggling to re-attain that lost respect, and this drives them to be intensely patriotic, the knowledge of a glorious past. We all think how great we were. Also, Asia is possibly the most embattled part of the world, that tends to keep morale and patriotic feelings high.
I'm from India , as u might have noticed, and its the continuous fighting with neighbouring Pakistan, lack of trust in the Chinese for their epic backstab of 1962 , and the fact that no one in particular likes us, except for Russia, that has hardened us and makes our soldiers fight to hold every inch of land that makes up our country. Their ferocity in combat is magnified cos of the fact that large portions of our land are occupied by our neighbours,China and Pakistan.
Regarding US patriotism and 9/11, i think US citizens have always been patriotic, just that 9/11 showed them that they were not safe as they thought they were, and opened their eyes to the problems of the world. A certain paranoid reaction kicked in, which isnt patriotism, its fear and hatred, not very correct emotions, and im glad its fading away.