The Transportation Security Administration processed more than 900 million travelers through U.S. checkpoints in 2025, according to TSA data — and during peak travel windows like spring break and summer, average checkpoint wait times at major hubs regularly exceed 30 minutes. What the agency is actually scanning for, and what predictably slows everything down, is something most travelers still get wrong every year.
Understanding how TSA screening works isn't just useful trivia. It directly affects whether you make your flight, whether your laptop ends up dented on the conveyor belt, and whether the officer waving you into a secondary inspection pod is going to make you miss your connection. The rules have also evolved significantly since the pandemic, and several common assumptions about what's allowed are now outdated.
TSA's primary screening technology at most major airports is the Advanced Imaging Technology (AIT) body scanner — the millimeter-wave machine that asks you to raise your arms. These scanners don't see through clothing in the traditional X-ray sense. They detect anomalies on the body surface, flagging anything that isn't skin or a thin fabric layer. That includes forgotten chapstick in a shirt pocket, a thick belt buckle, and — critically — any item denser than air in a carry-on bag that wasn't properly removed before the X-ray belt. The algorithm flags the area, and an officer must physically resolve the alert. That's the moment most secondary checks begin.
