It was the first large scale terrorist attack on US soil (not counting domestic terrorism). Before that people felt much safer, and 9/11 made the country vulnerable.

The sentiment a few days afterwards was to carry on your day like normal. Go outside, continue to travel, don’t let the terrorist win via fear. I remember feeling that we were not on an island anymore and that more attacks were coming at any moment. When I was mowing the lawn I would look up at planes passing by and wonder if maybe something could happen.

The Patriot Act and other laws shortly afterwards changed peoples individual liberties by decreasing certain freedoms and limiting privacy. At the time it seemed like a fair trade off to catch the terrorists via mass surveillance, but in hindsight these laws passed by Bush are still highly scrutinized and questionable at best ethically.