1 - The War on Terror. Al Qaeda is trying real hard to bring this war home to Americans. That they have not succeeded since September 11, 2001 has a lot to do with the energetic activities of American armed forces and police organizations.
In the meantime, there have been some "lone nut" Islamofascist attacks on America since 9.11.2001 even if the body count has been minimal. We've had Charles Bishop/Bishra who called his acts terrorist in his suicide note and pledged his support to bin Laden. We've had the shoe bomber who was stopped on the airline before he was able to commit his evil deed. We've had the DC sniper duo. We've had the shooting at the LAX counter.
There may have been more hope for a mass uprising against America than actually followed through but some Islamofascists did commit themselves to the movement.
We've also had a plane blow up mysteriously on take off and an anthrax murder case that is still unsolved.
Internationally there have been bombings targeted as allies of the United States in the war effort. America has been spared the brunt of the attacks but that is due in part to diligence and also in part due to our resolve.