That's likely due to the Voting Rights act which requires what they call majority-minority districts. It prohibits redistricting to disempower racial minorities. It's another complication in the whole gerrymandering debate that makes it a lot harder to solve, because it requires districts that will look gerrymandered in a lot of cases.
See, the Russell conjugation is that it demands gerrymandering, to keep Democrat strongholds blue. I'm really only speaking to the 10% of you who can think about this stuff without feeling those delicious squirts of tribal belonging, not the 90% of people who ignored what I said so they could yawp.
