Oil question...

The other day, while surfing the internet, on one of my news websites I saw the horrible news that there was an oil spill at the mouth of the Mississippi River. I then heard a small report on NPR explaining a bit more of the details... Now, forgive me for possibly getting some of the facts wrong, as I didn't have a notepad to write on while I was driving home and listening to the radio. The ship has spilled 419,000 gallons of fuel oil. (now here are the facts I heard, but can't seem to find confirmation of in some of the online news reports). They mentioned that the ship had just picked up the oil from a local distributor and was headed to some country, when it got hit by a tugboat.
Then it hit me...
Wait... did he just say that the ship was headed for another country?
We are currently in an Oil crisis here at home (USA).
There are talks of offshore drilling.
There are talks of drilling in the Alaskan wildlife refuge area.
If we need oil so bad... WHY are we exporting it then to other nations?
I googled it this morning, and according to this chart, the USA is the 17th ranked nation for exporting oil! (this isn't the same chart, but it still shows USA at 17th).

So can someone explain this to me?

[update: 7/27/08]
This news item just appeared on reddit.com tonight that goes to answering this question! I'm glad other people are paying attention to this.
Short answer if you don't want to read the whole article (which is short).

Large multi-national firms like Exxon-Mobil are not US property. They sell to the world and their allegiance is to corporate profits.