Does the Party List Matter?

Abstract

This note updates Gosnell's (1939, The American Political Science Review) analysis of United States elections under single transferable vote (STV), expanding its coverage and making the data available. Later work used the same cases to popularize (and respond to) the claim that proportional representation (PR) leads to 'fragmentation,' which in its original formulation meant an absence of two-bloc competition. I compare that definition to leading perspectives on systemwide STV behavior. Then I describe how party-list allocation based on observed first-choice votes produces seat distributions that are less 'fragmented' from whichever perspectives might apply to the case at hand. Rare but consequential differences are consistent with a range of non-party hypotheses about ballot marking. These results speak to an old taxonomic controversy and thus the terms of a recurring fragmentation debate.

Keywords: fragmentation, fusion, local elections, semi-proportional representation, single transferable vote