As mentioned, with Bulgaria and Romania being part of the Schengen space for air travel, passengers traveling between these countries and the US (or any other non-Schengen destination) would likely have to clear passport control at the connecting airport in a Schengen country like FRA, AMS, CDG, etc. Previously, passengers would have cleared passport control upon arrival/departure in Bucharest and Sofia, but now, since the flight from Bucharest or Sofia to the Central European gateway is an intra-Schengen flight, passport control procedures would likely be shifted to these connecting airports...