9/11's lasting overhaul: from TSA lines to cockpit doors

The article outlines how the 9/11 attacks triggered a sweeping redesign of US air travel security, shifting from generic screening to layered, risk-based measures (including TSA PreCheck), stricter baggage rules (3-1-1 liquids), and broader use of tech like full-body scanners and biometrics. It traces milestones—from the Lockerbie bombing prompting baggage checks, to the 2001 shoe bomber and the 2009 underwear bomber—and notes ongoing evolution toward cockpit protection with retractable gates on new planes, while acknowledging civil-liberties concerns over opaque criteria and watchlists.