What has changed in this country since 9/11?

It has been 17 years since 19 terrorists hijacked four commercial airliners in U. S. airspace, turning them into missiles that destroyed New York City's World Trade Center towers and damaged the Pentagon. The fourth airplane crashed into a Pennsylvania field. The attacks killed 2,977 people.

The Sept. 11, 2001, terrorist attacks are often described as an event that changed the country forever. It is a date that accompanies Dec. 7, 1941, as among the most infamous in American history.

Americans often speak of the terrorist attacks in terms of "before" and "after." Before 9/11, public buildings had fewer security measures, it was more difficult for law enforcement to get wiretapping warrants, and airport security measures were much less strict. After 9/11, the immigration system was radically overhauled, banks were compelled to take more responsibility to fight money laundering, and the United States entered into a military conflict in Afghanistan that has become the longest in the nation's history.

The attacks spurred temporary changes, too, such as a surge in American flag sales, and an increase in military enlistment as the United States went to war in Afghanistan and later in Iraq. The attacks prompted other seemingly permanent changes. Here are the 15 ways America has changed since that fateful day.

24/7 Wall St. examined media reports and government documents in recent years to determine the different ways the United States changed because of the 9/11 attacks. We discarded temporary changes and focused on the impacts that are still being felt in this country.