Replication Data for: Designing Electoral Districts for Proportional Representation Systems. How Electoral Geography and Partisan Politics Constrain Proportionality and Create Bias

Proportional representation (PR) electoral systems have grown widespread because they are expected to ensure the representation of interests with small or geographically inefficiently distributed voter bases. Yet in reality, most PR systems consist of a large number of districts that vary strongly in size and some have surprisingly low magnitude. Existing research shows that such differences matter greatly for political outcomes but offers no explanation for their origins. We argue that the design of electoral districts in newly adopted PR systems is systematically linked to electoral geography and partisan politics. If parties with concentrated voter bases can influence the design of the new electoral system, they will create a significant number of low magnitude districts. In general, parties involved in designing districts benefit from electoral disproportionalities under the new PR rules. Empirically, we use newly collected district-level data for several Western European countries in the early 20th century.