Back before the 2004 election, Harper’s magazine did a serious article about just how difficult it would be to actually leave the United States and never come back if George W Bush won the election. You are the property of the U.S. government after all. It’s not like the farmer can let the cows leave the pasture and not be milked.
The article is located [here]. I don’t think in their wildest dreams they wrote this thinking that people might start rereading it in 2009.