The Washington Post reports that blacks are increasingly migrating into the suburbs, making the GOP's "pack and crack" gerrymandering strategy even easier than it used to be:
“The practical effect is great for the GOP,” said Dave Wasserman of the Cook Political Report. “In state after state, it’s allowing Republicans to pack more heavily Democratic close-in suburbs into urban black districts to make surrounding districts more Republican.”
....Over the last few rounds of redistricting, Republicans have made a habit of “packing” as many reliably Democratic black voters into as few districts as possible, virtually guaranteeing black representation for those districts while also making nearby ones more winnable for the GOP.
In a way, this is almost a bipartisan, or perhaps biracial, strategy. Republicans like it because packing all the black voters in one place gives them more winnable districts elsewhere, and Democrats go along with it because it gives African-American candidates a chance to win congressional seats. Unfortunately, this is pretty much their only chance: only a handful of black members of Congress come from majority white districts because the sad truth is that, for the most part, white voters are still largely unwilling to vote for black candidates. And just to restate the obvious, this works out pretty well for Republicans, which goes a long way toward explaining why Fox News spent practically the entire summer last year scaring the hell out of white people.