I’m also assuming that you’re in the US; I can’t really answer for any other country.

9/11 was the worst terrorist or act of war attack in America in 60 years (since Pearl Harbor). America had gotten very complacent about a lot of things, including patriotism. We had gotten very used to our freedom and safety, and had allowed ourselves to be lulled into a sense of security.

The days shortly following the attacks, we were in almost in a state of panic. Everything seemed like it was turned upside down, and we didn’t know who to trust and who to blame (of our allies or enemies), since for the first time, America had been attacked by a terrorist force instead of a traditional attack by a nation.

Patriotism happened for several reasons. President Bush and other leaders went on every media possible to encourage Americans to stick together. People banded together to show that we weren’t going to be frightened into submission. The attack on our country, while it was meant to be a show of strength to frighten us, succeeded in “waking the sleeping bear” and reminding us to stick together, to not give up.

Throughout our history, any attack that has been waged against us has only served to band us together more strongly. Ever since the pre-Revolution days, no force has ever been able to get us to back down, because our country was founded on the love of freedom and equality. (Granted, not all people have found freedom and equality here, it took a while, but that’s another essay.) Our freedom, our equality, our chance to succeed that is not based on status, color, or belief; these are all things that we as Americans hold dear, and it’s something that no one is going to take from us.

9/11 has had many other impacts on our lives, of course; but these were the reasons for the patriotism afterward. You may remember people hanging flags outside their houses, or flying them from their car windows, or standing outside with candles while aerial photos were taken. You may or may not remember people wearing certain colors on certain Fridays to show their patriotism. And many history books have since been written, erasing the revisionist history that said that our founding fathers were other than they were. (Unfortunately the revisionist ones are still used in places, but true history is starting to be taught again).

Hope that helps!

Uniting people in order to fight one enemy brings everyone together and strips away petty differences and highlights the best in people; e.g., WWII.

9/11 did the same thing; look at how the passengers on United 93 got together and look what they were able to achieve!

So around the USA and other parts of the world, for a time, everyone was united in their condemnation of Bin Laden. We had another taste of this partiotism during Desert Storm.

The attack on 9/11 was a slap in the face for all Americans and we reacted accordingly. A close friend of mine draped his house in an enormous American flag; people put stickers in support of the USA on their cars; and put American flags on their car antennas. The common enemy; has that effect every time.

It is common in any group even small ones that any form of external attack helps the group to bind more closely together

This BBC article sums it up (it is no longer traceable unfortunately):

“How America has changed after 9/11:

I think Americans have changed considerably. September 11th of last year, flags went up everywhere; a sense of patriotism abounded. A year later it’s a sense of a mellowed patriotism, a thoughtful patriotism. Americans aren’t afraid to be patriotic and want to think about it.

Secondly, I would say Americans are more thoughtful about foreign policy and domestic policy and, thirdly, I would say Americans are looking inward to things that are important to them; their families, their churches, service in their community — things that in the long run will be good for them and their families and their lives.

Some of the changes are all too obvious. This is now a very security conscious nation. The feeling of safety provided by two mighty oceans now gone, Americans no longer get on planes as if they were buses or go to baseball games without a brush from a metal or explosives detector.”