Could Obama Carry Mississippi in the General?

Unlikely.

Because Mississippi is holding its primary today, and because Senator Obama has been relatively successful at increasing African American turnout (more about that below), there has been a little bit of chatter about whether or not Obama could actually win Mississippi against McCain in the general. The chatter basically centers around the fact that Mississippi has the largest share of African American residents in the country (save for DC). Theoretically, if Obama could get Black voters to turn out in big numbers, shouldn't that put Mississippi in play? Let's look at the numbers.

According to the 2006 American Community Survey run by the US Census, about 37% of Mississippi residents are African American, and 60% of Mississippi residents are white. Let's assume, for the sake of argument, that Obama wins 90% of the Black vote in Mississippi. If African Americans turn out in proportion to their overall share of the population (which they didn't in 2004), then Obama would still need about 27% of the white vote to win. That doesn't sound like much, but in 2004 John Kerry only managed 14% of the white vote. Take a look at the graph:
Click on the graph to expand.

Basically, what we see here is that, in order for Obama to win Mississippi, even with 95% of the Black vote, he would need two things to happen. First, he would need Black turnout to exceed the actual share of African Americans in the state. Second, he would need top improve his showing among whites over Kerry's totals. Both need to happen. For example, say African Americans are really motivated, turn out in huge numbers and end up making up 41 or 42% of all voters (exceeding their real share of population by 4 or 5 points). That would be a huge turnout and an amazing accomplishment for the Obama campaign. But even then, Obama would still need to outperform Kerry by a several points among white voters.

Still, there is a somewhat plausible scenario under which Mississippi could go blue. Imagine Black turnout exceeds real population share by 1 or 2 points (possible, but still difficult) and Black voters make up 39% of all voters. Imagine further that 95% of all Black voters cast their ballots for Obama (very possible). Senator Obama would still need about 22% of the white vote to win. While Kerry only got 14%, in 2000 Al Gore got closer to 18%. Obama would need to outperform Gore by 4 points. That'll be difficult, but not totally outside the realm of possibility.

So, as I said, unlikely.