I know the popular sentiment is that environmentalists are to blame, but in reality, environmentalists have had no power since control of Congress and the Presidency was in the hands of the Republicans. We obviously should process more oil, so the price goes down, and our refineries are supposed to be operating at full capacity, so why not build more where we already have some? With fuel prices as they are, the populace would support it.
One of the problems is probably that it's more logistically practical to have them in Asia, where all the by-products are used to make plastic and crap for mainly U.S. consumption. If we increased refinery capacity here and had the by-products in the U.S., then we might "heaven forbid" use them to manufacture things in our own country.
If the oil companies aren't willing to build a refinery, the U.S. should build a few, run them, and provide cheaper fuel to compete with the Exxon/Mobil suits who are reaping the windfall profits off of our backs to build their McMansions and buy their yachts.