Examples that illustrate how compactness and respect for political boundaries can lead to partisan bias when redistricting

To reduce the unfairness incurred by partisan districting, citizen reformers usually advocate applying the conventional criteria of compactness and respect for political boundaries of subdivisions. Simple examples are constructed to address whether optimizing these criteria also minimizes partisan bias, measured as the difference between the seats-votes curves for the two parties. One set of examples shows less bias for less compact districting, supporting the comment of Grofman and King that compactness is not a reliable proxy to achieve partisan fairness. All examples indicate that respect for political boundaries increases partisan bias, well known as unintentional gerrymandering. These examples are consistent with the contention that partisan bias should be confronted directly and minimized when redistricting.