KEY POINTS
  • Before the Sept. 11, 2001 terrorist attacks, passenger screening was comparatively minimal.
  • Screening has ramped up, creating long lines at airports and other hassles.
  • Security experts say risks remain and are evolving.
Smoke continues to billow from the remains of the World Trade Center as Continental Express planes sit at the closed Newark, New Jersey Airport 12 September 2001 in the wake of the terrorist attack on the World Trade Center. One of the hijacked planes departed the Newark Airport and later crashed near Pittsburgh, Pennsylvania.

More than a fifth of the U.S. population is too young to remember what air travel was like before Sept. 11, 2001.

Passengers' loved ones used to be able to greet and bid them farewell at the gate. Travelers weren't required to take off their shoes and belts or remove liquids from carry-on luggage before going through checkpoints, let alone wait in long security lines. It was years before airlines charged passengers to check their bags or select a seat, though average domestic fares are cheaper today.