Originally Posted by fastair

Gonna guess you haven't asked an on the job CBP officer. I have. You'd be surprised how little they care about your onward connecting flight and how much they do care about their job, and having the owner of the bag be present when it clears customs. Are there procedures in place? Yea, of course. Do they keep a record of every unclaimed bag, including the name of the owner? Yea, they do. What they do with that is beyond my knowledge, but from years of working the customs hall, I've heard a total of one "yea, it's ok to leave your bag behind and make your connection." That was from a new CBP officer and his chief pulled him aside immediately. No clue what how that conversation played out, but I never heard that answer again.