I have written this new piece for Slate.  It begins:

As Democrats struggled last week to salvage control of the Senate, they pushed to get as many black voters to the polls as possible, especially in the South. It’s no wonder: Blacks are the most reliable Democratic voters, and 89 percent of them ended up supporting Democratic candidates in the 2014 elections (a mark that was actually down from 2012). White voters, in contrast, came out heavily for Republicans in the South. In North Carolina, where incumbent Democrat Kay Hagan lost to Republican Thom Tillis, the GOP candidate got just 3 percent of the black vote. But as we all know, the black turnout was not high enough to beat back the Republican wave in North Carolina or elsewhere. In North Carolina in particular, black turnout was down compared with 2012.

Recognizing this major overlap of race and party in the South is key to understanding Wednesday’s Supreme Court case involving a constitutional challenge to Alabama’s legislative redistricting. No one disputes that the Alabama legislature packed black voters into a few legislative districts, thus strengthening Republican control in the majority of districts throughout the rest of the state. But whether or not that action is constitutional depends a great deal on whether the court views this as a case about race (in which case Alabama may have acted unconstitutionally) or one about party (in which case Alabama’s actions are constitutional, if unsavory politics as usual).