The map to the left shows the counties which voted for Obama (blue) and McCain (red) in the 2008 election. The blue counties are part of the Black Belt, the area where blacks are a majority of the population because of the economic concentration of cotton culture during the 19th and 20th centuries. The McCain Belt, those counties where John McCain beat George W. Bush, is getting some press, but obviously it is interesting to wonder about areas where large black populations which increased turnout are likely masking the shift of the white vote for John McCain. I have already shown on a state-by-state basis where the white vote shifted toward the Democrats in 2008, and where it shifted toward the Republicans. Though the average white vote budged only a bit, there is important regional structure which is being masked by aggregating all this information. The political scientist Larry Bartels reaffirms my basic point:
However, there is a good deal of circumstantial evidence suggesting that racial resentment eroded Obama's support among white voters. His gains relative to Kerry were significantly smaller in states with large numbers of African-Americans--a pattern disguised in the overall vote totals by his strong support among African-Americans themselves. In the former Confederacy he gained only slightly over Kerry among white voters, despite making big gains in two key swing states, North Carolina and Virginia. The only states in the country in which he lost more than a point or two of white support were Louisiana, Alabama, Arkansas, and Mississippi.
You can see this in the exit polls. They rather straightforwardly illustrate that Obama won a smaller percentage of the white vote than Kerry in many states in the South. But I decided to look at it a different way: I plotted the percentage of whites in each county and their vote percentages for Barack Obama and John Kerry in Mississippi. This is more precise than an exit poll because votes are votes, and the Census counts everyone. So here is that chart:
As you can see, as the percentage of whites increases the proportion voting for the Democrat decreases. This is no surprise. In this part of the South the Republicans are the white party, and the Democrats are the black party. But look at the slopes: it is higher in 2008 than 2004. That means that the white vote for Obama was lower and the black vote for him higher. The "ends" of the line swiveled so that the slope tilted up. If I assume that this is modeled by a linear regression, the r-squared for 2008 is 0.93 and for 2004 it is 0.76. If I assume that this is a logistic curve the r-squared for 2008 is 0.90 and for 2004 is 0.81. The r-squared can be interpreted so that one can say that ~90% of the variation on a state wide level in voting for Democrats could be explained by the proportion who were white in the counties in 2008. In 2004 the equivalent value would be ~75-80%. Both of these values are high, but, it suggests that the exit polls are right, and racial polarization has increased over the 4 years. Whiteness is a nearly perfect proxy for the Republican presidential vote now, and blackness the Democratic vote. And these associations have increased between 2004 and 2008. But it isn't as if Mississippi is one homogeneous state with one culture. Among whites there are those who are basically in Appalachia, while others who live in the lowland South. So I decided to constrain the chart to counties with various intervals of the white %. Here is a chart of only the majority black counties:
Here are majority white counties:
And here are counties where 62% or more are white, which is the proportion in Mississippi which is white (so these are the whiter counties in the state):
It looks to me that what you're seeing are two things: 1) Increased black turnout in counties where many blacks weren't voting. I think the black turnout went up nationally by about 10% (that is, from 11% to 12% of the electorate), but there might be regional disparities in terms of where that 10% is coming from. 2) Some white people in mostly white counties switched from Democrats to Republicans. I assume in majority black counties you're pretty much as polarized as you can get; very few white Democrats and black Republicans. In the overwhelmingly white counties there's less polarization because the fact that there are few black people means that white Democrats aren't a member of the black party, at least locally. But it looks like the emergence of Obama changed things even in very white counties, where there is a discernible drop off in white support, with obviously far less compensation from the relatively small black minority turning out a higher rate. If you're wondering about what that one outlier on the chart which is far away from the trendlines, it's Alcorn county in Mississippi's far north. It's not a data entry error, that was my first thought.... Here's the raw data:
WhiteObamaKerry
Adams435955
Alcorn87.82761
Amite56.64442
Attala52.54238
Benton654853
Bolivar33.46764
Calhoun70.13535
Carroll65.23434
Chickasaw57.55049
Choctaw68.53533
Claiborne14.68582
Clarke65.53732
Clay42.55952
Coahoma25.37364
Copiah48.45343
Covington63.24138
Desoto78.83027
Forrest62.54338
Franklin63.23735
George90.11622
Greene72.52427
Grenada57.42441
Hancock90.421.229
Harrison71.836.636
Hinds32.47060
Holmes18.28276
Humphreys25.67164
Issaquena39.36153
Itawamba92.52129
Jackson74.73230
Jasper46.95551
Jeff Davis41.76151
Jefferson13.58781
Jones71.63028
Kemper37.96353
Lafayette72.34340
Lamar83.52119
Lauderdale57.74034
Lawrence67.73736
Leake County55.64440
Lee72.33433
Leflore28.26862
Lincoln68.93431
Lowndes54.65838
Madison60.64235
Marion66.23433
Marshall50.35959
Monroe68.44140
Montgomery53.84645
Neshoba64.22625
Newton65.23227
Noxubee29.17671
Okitbbeha58.25043
Panola51.45249
Pearl River86.31923
Perry76.32725
Pike49.35147
Pontotoc84.52323
Prentiss84.92832
Quitman306760
Rankin79.42320
Scott59.64337
Sharkey30.66850
Simpson64.63932
Smith75.82421
Stone79.52727
Sunflower27.17063
Tallahatchie395955
Tate68.43939
Tippah81.32733
Tishomingo95.42334
Tunica26.67669
Union842427
Walthall54.74439
Warren51.94941
Washington31.36759
Wayne61.53936
Webster78.12526
Wilkinson30.16964
Winston54.64553
Yalobusha60.24644
Yazoo44.15745
