Whatever the purpose, immigration lines at airports (and border crossings) and security lines at airports generally share one characteristic: You stand in line anywhere from minutes to hours for a face-to-face transaction that takes no more than a minute or two. The rest of the time is totally unproductive waiting and queuing.
Fortunately, a few programs let you avoid some of the worst of those lines, at least sometimes, and at some airports and borders. The federal government, through U.S. Customs and Border Protection and the TSA, operates a handful of robust programs, both here and abroad. And a few private ventures have tried to move into the airport security process with limited success; presently, only one—Clear—seems to be operating.