There was a reason why the inhabitants of the District of Colombia were not allowed to vote.
It’s been so long since I’ve studied it, I’ve forgotten the reason.
It may or may not make sense any longer.
It is interesting the way things work in the District compared with Puerto Rico, as you have laid them out here.
In the 1970s/1980s the black population of DC was around 70%. Currently it is now down to about 50%. However, so far as Congress is concerned since the vote is over 90% Democrat, fairness will not enter into Congressional decisions re DC. DC has 3 electoral votes, recent local Republican activity has been to promote DC’s becoming a territory, thus paying no taxes. This would make the 1% very happy as well as big developers and the politicians they pay off (who are almost all Democrats).