Electoral Systems: Divisions, Constituencies, and Gerrymandering

Single Electoral Divisions

Electoral systems often feature divisions within their territorial scope, where all votes are aggregated to implement the chosen electoral formula. This constituency structure is found in elections to the European Parliament, and also in local elections where each municipality serves as a constituency.

These constituencies may have different magnitudes. Districts with a minimum magnitude, often a single seat, are called single-member constituencies. When they are assigned more than one seat, they become multi-member constituencies. Multi-member constituencies can be categorized by the number of seats:

• Low-magnitude: 2 to 6 seats
• Average-size: 7 to 14 seats
• High-magnitude: Over 15 seats

Multiple Electoral Divisions

In systems with multiple electoral divisions, the electoral territory is divided into units that form the framework for the election of one or more seats. Congressional elections, for instance, often feature multiple multi-member constituencies where most units have fewer than 7 seats. This often leads to results similar to those obtained with the application of a majority system.

Electoral Districts and Gerrymandering

In majoritarian systems, the territorial election unit is typically called an electoral district, which is usually relatively small. The setting of these districts allows for greater freedom and easier redistribution compared to land-based divisions, as they primarily rely on demographic bases. This flexibility has, however, led to excesses and corruption, notably through the technique of gerrymandering.

This technique has been described by Mackenzie as "the readjustment of electoral boundaries for any purpose unrelated to equal representation," generally to benefit the party in power.

Gerrymandering has a simple mechanism: If the preferences of the electorate in single-member districts are known, it is relatively easy to manipulate the desired results. This is often achieved by strategically redrawing district boundaries, for example, by transferring voters whose vote is crucial from one district to another to achieve the required number of votes for a candidate of the favored political party to secure victory in the latter district.

In conclusion, electoral districts of high magnitude tend to hinder arbitrary manipulation of electoral choices, thereby ensuring that the will of the electorate has a more solid reflection in the representative body.