I agree with Bart's posts here except his view on the lengthy lines. In 30+ years of frequent flying, I have encountered long lines on occasion prior to September 14, 2001. But the wait times at airports all over the country jumped dramatically (for me, at least) on September 14, 2001.
Note that I'm not blaming the TSA for the drastic slowdown in checkpoint throughput. Idiot Mineta's "Spend lots of time searching for many non-credible dual use items" policy is to blame.
Problem is, the TSA inherited his prohibited items list lunacy, and his subsequent shoe lunacy (check nearly all of 'em in our risk avoidance strategy), and the lines are still far too long. Only recently has the TSA relented on some of the nonweapon items, and it ignored the most obvious (and most hated, by me) stupid prohibition: small penknives.
In many airports, the TSA checkpoints occupy several times the square footage of the old checkpoints. Example: AA was in the process of remodeling its T-4 terminal prior to 2001, and part of the work was some nice new terrazzo flooring on the upstairs entrance to the concourse, where the security checkpoints have always been. The three x-ray machines and WTMDs occupied, at most, several hundred square feet. There was lots of open space and even newstands and other vendors up there.
Well, along comes the TSA, and that agency now occupies several thousand square feet - it now occupies the entire upstairs entrance to the concourse. It's squeezed up against the stairs and escalators. TSA added several more x-ray machines and WTMDs and hundreds of linear feet of plexiglass holding pen panels. Yet long lines are still typical.
Oh, about that nice terrazzo? Can't see it anymore, as TSA has covered it with numerous machines and plexiglass pens. Holding pens? Never saw them, pre-TSA. Obviously we are safer because of them.
Bottom line: Almost Nobody had to undress in the old days. Belts, shoes, jackets, etc were all ok to go. The cowboys with Dinner-plate-sized belt buckles and the stoners and rural hicks with their huge chain-secured wallets were the exceptions. Now, traversing the checkpoint looks a lot more like a prison intake procedure than it ought to. And that's shameful. I still don't understand how Americans can treat fellow Americans so disgracefully. Perhaps the larger federal paycheck (much larger than under the old system) convinces them.