Fascinating Harry Enten for 538:
Now, however, it’s much more difficult for black voters in the South to find enough allied white voters to elect the representatives they want (almost always Democrats). There are just so few white Democrats left in the South, especially in the Deep South, compared to 10 years ago. It’s made drawing maps that meet VRA standards trickier. This problem is at the heart of two Congressional gerrymandering cases the Supreme Court heard on Monday, one from North Carolina and one from Virginia. The Court will have to decide how the VRA applies now that race has become such a strong proxy for partisanship in the South….
his difference makes it much more difficult to elect a Democrat in the South now — you need many more minority voters to do it. Given how nonwhite people voted compared to the nation as a whole in 2014 (45 percentage points more Democratic), the average district now needs to be less than 54 percent white in order to elect a Democrat in a neutral year. (According to the CCES, whites make up 69 percent of all voters in the South.) If whites were still as Republican-leaning as they were in 2006, the average district could be as much as 65 percent white and still expect to elect a Democrat in a neutral year.
When we focus solely on black voters — rather than nonwhite voters generally — the shift is just as dramatic. Southern black voters were 77 percentage points more Democratic than the nation in 2014. In a hypothetical district with only white and black voters, whites would need to make up less than 67 percent of voters to elect a Democrat in a neutral year. If whites voted the same way they did in 2006, a district could be about 77 percent white and would elect a Democrat, on average.
That’s a tremendous difference from a decade ago. That means the VRA is once again becoming increasingly important to Southern black voters’ ability to choose their representation in Congress. Although districts don’t need to be majority black, they need to be far closer to it.