In Atlanta, passengers are doing the airport three-step: Shoes off, a quick X-ray, and then shoes back on.
This focus on the feet all began after Richard Reid tried to blow up a jet with a bomb hidden in his shoe in December 2001.
Some passengers complain that it makes them late, but frequent flyers say what bothers them most is the seeming inconsistency.
"If you go to Colorado Springs, man, they check you like you're the president," says traveler Ray Derstine. "And then when you go into Denver, they're not as strict. When you go to Philadelphia, it didn't seem to be as strict either."
The Transportation Security Administration (TSA) says shoe removal is not mandatory at any airport. But its Web site advises: "Screeners may encourage you to remove them before entering the metal detector as many types of footwear will require additional screening even if the metal detector does not alarm."
Despite that, more and more passengers are wearing shoes that don't alarm. Shoeshine guys say they're seeing more sneakers and sandals than anything else. And some shoe makers are now marketing airport-friendly dress shoes, made without any metal in them at all.
Security experts say this new airport shuffle is likely here to stay, keeping passengers and TSA agents on their toes.