I'm interested in finding out a little history on how International Transit has worked historically in the US. I know that the current situation is that transit is not permitted and all passengers must enter the US prior to transiting, but I am wondering if it has always been that way.
The thing that piqued my interest into this question was arriving into Tampa International Airport, and walking past a room (in the International Arrivals corridor toward Customs/Immigration) with a door labelled "In Transit Passenger Waiting Area". This room was full of junk, and obviously not in use; but it implies it was in use at one point!
Does anyone know what this room would have been used for in the past, and how transit worked before the rules presumably changed? Also, how many other airports had/have similar "rooms"/areas?