Airport
The biggest focus is on metal objects in an airport. As soon as you ping that metal detector they look at you closer. Having your cash in a non-metallic environment can't hurt, I suppose! In recent years, they do an addition random lotto style "Let's search this one EXTRA good" thing for good measure and to justify their jobs and all that. I have always been concerned about carrying large amounts of cash also and have gone to extraordinary measures for optimum concealment with much more paranoia of some "official powers that be" throwing their weight around than some desperado looking to steal it!
Another good point was made about just driving down the road also! Amazingly enough, in many places I hear that the police will flat out ask,"How much money do you have or are carrying with you?" and if it's enough they confiscate it! I heard this is a popular practice in Texas and Louisiana in particular. That television show "60 minutes" did an episode about this and went into how an older couple, retirees were on vacation driving through some place 'er other and the state troopers did this to them, taking their approximately $5000 in cash which was their vacation funds for no particular good reason and they played hell to try and get it back! Imagine spending $6600 in attorney's fees to get back your $5000 and have your vacation ruined on top of THAT! Wonderful country America, eh?
The premise of this confiscation was that "obviously this much be some sort of drug money since it's so much"... but the retirees in question had no drugs, no criminal record, no probable cause, no nothing... they were just ancient old people driving off on vacation... with a pathetic $5000 on them---Really not that much money. I think I am just as concerned about simply driving down the street with any significant amount of cash on me as flying on a plane with it. Taking it on a plane might even be SAFER!
My thoughts and advice are to be careful in ANY instance when traveling with cash. Take adequate precautions! I often carry too much money on me to not take every possible precaution.