Originally Posted by cordelli

When you enter the US, be it Newark or Philadelphia, I would assume you would have to go through immigration, pick up your luggage, and clear customs.

Are you saying in Philadelphia you don't have to do that?

Once you have access to your checked bags, again no matter what airport you are at, you will need to clear security again before you can get into the sterile area.

Unless you were on a flight that was precleared in the the country you started in I don't see how it's possible to avoid immigration, customs, and a security check in Philadelphia. I don't believe that is possible in Zurich, at least not according to the list of preclearance locations on the customs website.