With the 10-year anniversary of the 9/11 attacks, Channel 4 News is looking at the measures that were put in place afterward to protect public safety.
The most obvious way to see the security changes in action is to visit the Nashville International Airport and think about the way flying used to be.
"You'd show your ID at the counter when you'd get your ticket, you'd go to the gate and bring your friends with you to see you off," said traveler Curtis Griffith.
The process of showing your identification and boarding pass before the security line, removing your shoes, putting your liquids in a Ziploc bag to set aside and stepping into a full-body X-ray machine all came as a result of 9/11.
Security is also a lot stiffer than it used to be beyond the security checkpoint.
"Once the individual gets through the screening process, we also have other layers of security. Our flight deck officer program, our pilots are armed, we have armored doors aboard the aircraft, as well as federal air marshals," said Federal Security Director of the TSA at Nashville International Airport Paul Armes.
You also see extra measures when you have your bag searched and get a pat down before a Titans game or a concert.
Less visible though is a safety infrastructure set up to make sure authorities tell each other about perceived threats.
"That was a great concern after 9/11 that there wasn't enough personnel at the state and local level that had clearances or had access to the information to understand the national threat picture," said Supervisor and Intelligence Officer for the Tennessee Department of Safety and Homeland Security Steve Hewitt.
Tennessee has one of 71 law enforcement fusion centers set up across the country that puts local, state and federal investigators all together under one roof.
"The difference after 9/11 and now is light years. It's all about time. It's all about being able to quickly identify crime, the individuals involved in a crime and having people within the fusion center and the databases that we've built with Homeland Security. It allows us to gather that information right at our fingertips instead of having to make a phone call and wait for that information," said TBI Special Agent in Charge of Criminal Intelligence Jerri Powell.
Some of the initiatives undertaken across the U.S. in the name of security have raised concerns about rights to privacy.
"The government surveillance that is taking place in this country is unsurpassed. Individuals without probable cause are being searched. They're being detained in airports. They're being detained in jails and prisons basically or often because of their religious beliefs," said Hedy Weinberg with the American Civil Liberties Union of Tennessee.
The ACLU litigates and lobbies against measures taken since 9/11, including warrantless wiretapping and suspects being held indefinitely without trial at Guantanamo Bay.
"The conversation has to continue. We have to as a nation urge, demand that our elected officials not only ensure our safety but ensure our constitutional guarantees," said Weinberg.
One security measure taken since 9/11 is changing due to concerns about privacy. The full-body scanners at Nashville International and other airports are being altered to block the controversial naked images of passengers.
Tennessee has received $500 million federal dollars in the 10 years since 9/11 to improve Homeland Security.
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