Gerrymandering isn't the only solution there. If you're the secretary of state for a given state of the union, and you're in charge of the voter rolls, and you

Gerrymandering isn't the only solution there. If you're the secretary of state for a given state of the union, and you're in charge of the voter rolls, and you're running for office, then you are fully empowered to just remove anyone from the voter rolls who has a name you don't like, or who has a race you don't like, or who has a political affiliation you don't like. And you can stymie all attempts to uncover your malfeasance by just shoving all those requests in the drawer, where they get mysteriously lost.