Why such a big swing towards Obama? None of the counties around it swung Democratic.
It has basically no people. The surrounding counties actually have residents. Weird swings happen in tiny towns, especially hyperpartisan tiny towns. Obama only got 2 more votes than in 2008, but Romney got 70 fewer votes than McCain.
It has an aberrantly large Hispanic population compared to the surrounding area, possibly related to the below.
It's also home to this:
http://en.wikipedia.org/wiki/U.S._Sheep_Experiment_Station