Air travel has become increasingly annoying and enervating: delayed flights, more restrictive rules on the size of carry-ons (anything bigger than a wallet may force a gate check), delayed or lost luggage, long check-in lines, etc.
While the Supreme Court has recognized three exceptions to the border search doctrine (which may require a heightened suspicion for more detailed or delayed searches), the general rule is that whatever you carry with you into the U.S. you can expect to be searched and that you have tacitly agreed to such a search.