I wonder how far back this study goes though, because they're mentioning data from the Johnson years, and to conduct any sort of analysis utilizing nominal political affiliation before the 70s is kind of

. Either way, the trend is interesting and I'd like to know exactly what factors are causing this divergence. The authors mention affirmative action, but surely this trend is too large for that to be a meaningful factor. Blacks are disproportionately poor,
so I suppose if the Democrats were the party of the poor, blacks would be swept up in that tide, but I'm not comfortable making that claim. Also, I know this thread is about the presidency, but state and local level politics is usually far more important to the actual standard of living for people than federal politics.