Oh I dunno, Gettysburg, 3 days of American casualties to the tune of 40-50,000 people. Pearl Harbor, which directly lead to how many hundreds of thousands of US casualties? 1814 when the US CAPITOL was burned by the British? San Francisco earthquake in 1906 killed roughly 5,000 people. The 1929 stock market crash did not take its toll in bodies but in many ways much more harmful to the nation. The most horrific part of 9/11 is the way it's being used to erode our freedoms through the guise of "security." Increased police state, phenomenal increases in government spending, spying on US citizens, detaining people without due process, basically the government walking all over the 4th, 5th, and 6th amendments. TJ, Patrick Henry, and George Mason would be spinning in their graves if they saw the level of federal government power today.