I had retired from the Navy after Desert Storm. When 9/11 happened in 2001, I was in my second career. I woke up that morning with the radio telling me about the first plane, and snapped the TV on no more than three minutes after it hit. I watched the rest of the planes hit, and after the second tower was hit, I knew it was terrorism, and I knew it was Al Qaeda. I watched as our first responders performs nobly. I grieved with the rest of the nation. I was not alone in this, as many people I knew actually knew somebody in one of the towers, either a survivor or a victim. Every time I get on an airplane, or go to a ballpark, I'm reminded that eternal vigilance is the price of freedom.
I cannot presume to speak for 300+ million people, but personally, at first I was so enraged that I wanted to do serious harm to anyone that looked or smelled Muslim from the Middle East. I wanted the country of Afghanistan to be turned into the world's largest dry lake bed. In fact, when I have seen videos of people leaping from the upper floors to escape the flames I still feel pinches of rage. Now? I just feel minor melancholy. 9-11 also impacted my working life in a seriously irritating way by taking precautions that bordered on the absurd, but I won't get into that here.