Preclearance allows air passengers to fulfill US customs and security requirements before entering the country. Currently, there are 13 airports outside the US that have preclearance facilities. How does preclearance work? Basically, you present yourself to a US customs post in an airport and go through a process similar to what would happen if you were to be processed upon arrival in the US. it's just like arriving on a domestic flight. What's the advantage? There are a multitude of...