America’s top export in 2011 was . . . fuel?

Fuel is now the top U.S. export. The Associated Press reports that America is on pace to ship out more gasoline, diesel and jet fuel than anything else in 2011. (Aircraft, motor vehicles, vacuum tubes and telecom equipment were next on the list of top exports.) Granted, this is only for refined petroleum products — and those exports are still dwarfed by America’s much, much larger imports of crude oil. Still, it’s the first time fuel has been our top export in 21 years. So how did this happen?

Refineries in Deer Park, Texas. (David J. Phillip/AP) UC San Diego economist James Hamilton has a more in-depth analysis. Perhaps the biggest factor, he writes, is the glut of new shale oil in North Dakota. Since there’s not enough pipeline infrastructure to get all that oil down to the Gulf of Mexico for export, it’s been piling up in Cushing, Okla. That makes it cheap for refineries in the Midwest to refine it and ship it out than to simply ship the oil directly.

It’s also worth noting, as energy analyst Gregor McDonald points out in comments on Hamilton’s piece, that U.S. oil consumption has declined since 2006, which means that much of the refining capacity the country added in the past decade is now geared toward exports.