The Race Chasm

This analysis is taken from electoral-vote.com.
Progressive author David Sirota has an interesting observation about where Barack Obama has done well and where he has done poorly. He constructed the graph below, which shows how well Obama did as a function of the percentage of the population that is black.

What it shows is that in states with few blacks (like Wyoming and Idaho) Obama does well. In states with many blacks (like Georgia and Mississippi) he also does well. However, in states with a medium concentration of blacks (like Ohio and Tennessee) Clinton does well. What's the explanation? Sirota says it is race. In places like Wyoming and Idaho, race simply isn't an issue. There are so few blacks in these states that many people don't even know a black person, so race is simply not part of anyone's daily life. In contrast, in George and Mississippi, it is a huge part of everyone's life, but since most whites are Republicans, blacks make up a very large percentage of the Democratic voters (often approaching 50%) and their overwhelming preference for Obama has carried him to victory.

The problem for him comes in the states with enough blacks that race is definitely an issue but not enough to affect the election much. This theory would predict Clinton victories in Pennsylvania, Indiana, and Kentucky and Obama victories in North Carolina, South Dakota, and Montana.