If you tried to set a price that was substantially different from that which you experience south of the border, it would manifest itself in another fashion. It could be a supply shortage, because product moves to the highest price, and in this case, whether it's gasoline or corn, it's a commodity, and the supply is going to go to the highest price. Therefore, it's the events south of the border that would have acted to shorten supply, that would have caused a supply increase, that would cause supply to move to that area.
On June 18th, 2007. See this statement in context.