Because our refineries are producing more gasoline, diesel, jet fuel, etc than is used in the US.
Maybe regulation makes it difficult to sell here?
No, they are still meeting the US demand, they are just making more.
This is a good thing. After many years of expanding our existing refineries, combined with our falling demand, we finally have some surplus refining capacity.
So we import a bit more crude oil than we need, refine it, and sell the products at a higher cost than the crude oil. It keeps our refineries running, keeps more jobs in the US, and it helps our trade balance.
Thanks! I knew you would know.