I read quite often that gerrymandering of political districts is a cause of the current mess of our republic. That’s fine and makes sense but this is a bit abstract how drawing the lines can make sure the Republican districts always stay Republican and Democrat districts stay Democrat. Or how overall it’d really affect anything. You’d think the law of large numbers or such would even everything out. This image and description from Wikipedia makes it clear why it doesn’t even everything out very well – this is all from the Wikipedia article on gerrymandering.
Example for a state with 3 equally sized districts, 15 voters and 2 parties: Plum(squares) and Orange(circles).In (a), creating 3 mixed-type districts yields a 3–0 win to Plum—a disproportional result considering the state-wide 9:6 Plum majority.
In (b), Orange wins the urban district while Plumwins the rural districts—the 2–1 result reflects the state-wide vote ratio.
In (c), gerrymandering techniques ensure a 2–1 win to the state-wide minority Orange party.