How effective do you think the terrorists were in damaging the United States as a result of the attack of 9/11?

The terrorists did what they intended to do and scarred the United States, as well as make its economy fall.
The World Trade Center was a massive hub for the United States, so damaging it was effective because it effected every US citizen and made everyone fearful/wary of future attacks or the lack of security in the USA. The damage was done well, so the USA began to put more security on everything, especially airports.