Think of it like this... If a pipeline runs to an east coast port to fill up ships to export to Europe, and another pipeline is set up in Los Angeles to distribute product from the Persian Gulf to gas stations, it's easier to keep doing that than to send a super tanker that doesn't fit through the Panama Canal from that east coast port, around South America, to get it to the port of LA. That's just a hypothetical example, but most of our petro infrastructure was developed before we discovered fracking and started producing enough to cover our needs, and it's expensive to redo everything.