Here's a national county map using Castro's formula. So far, it correctly predicted Sanders winning every county in New Hampshire, although it was a bit generous to him with the margins, and (excluding ties both in the model and in reality) it got 60/90 counties in Iowa, predicting 23 Sanders counties would go to Clinton, and two Clinton counties for Sanders, for a generally Clinton-favorable prediction. But of the 100 non-tie (in model and in real life) counties to vote so far, it's correctly predicted 70, which is a pretty darn good record for just a formula and Facebook likes.
lol I can believe Whatcom County Washington. Obama won it 3-1 in the 2008 caucuses.
Edit; And another fun fact, Jesse Jackson won it in 1988, so my home has voted for 2 black candidates so far!