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.

Electricity is the answer