ELEVEN YEARS AGO, America suffered a blow that shifted this country as surely as any movement of its tectonic plates. On that sunny September day, terrorists attacked the U.S. homeland. Not since Pearl Harbor had the country felt the impact of a direct assault; not since the assassination of President Kennedy had there been such a national shock. And like those two horrors, the 9/11 attacks would soon come to define a point at which our country--and especially a generation--changed course.

Because of 9/11, the United States launched the "global war on terror," military actions in Afghanistan and Iraq that have, to date, cost the country over $1.29 trillion. More than 6,000 military members have died, with in excess of 43,000 wounded. Thankfully, the mastermind of Bloody Tuesday, Osama bin Laden, is dead. But extricating our soldiers from post-9/11 battlefields has proven difficult.

Because of 9/11, some Muslims (and even some turban-wearing Sikhs) were immediately targeted for harassment and retribution in the United States. Experts such as Adrienne Fulco, associate professor of legal and policy studies at Trinity College, credit President George W. Bush, who asserted that "America is not at war with Muslims," with calming that impulse. But tensions regarding Islam still surface. Think of the outrage a couple of years back over plans to build the "Ground Zero Mosque"; recall the protests over "discriminatory policing" in New York.

Because of 9/11, "evil" re-entered the American vocabulary, re-emerging from the mushy thinking of relativism with a clarity not seen for decades.

Because of 9/11, Congress created the Department of Homeland Security, consolidating several agencies (including the Secret Service, Immigration and Customs Enforcement, the Coast Guard, and FEMA) under one head, for better or for worse. Although the FBI remains independent, its primary mission has shifted from investigating crimes after the fact to preventing the next terror attack.

Because of 9/11, every American has felt the impact of increased security measures, from standing shoeless in lines at the airport to observing steely-eyed guards walking Amtrak trains to having their Internet and international phone-call traffic monitored by federal officials. Soon drones may fly over your hometown. If so, credit 9/11.