Patterns of regional and local council size

There is a growing literature that examines how subnational assembly size affects policy outcomes like turnout and women's representation, but also infant mortality and school enrollment. Political scientists know little about what shapes subnational assembly size, however. In this article, I analyse three possible explanations: firstly, building on the work of Taagepera, I propose that population size and assembly size are related: larger populations require greater assemblies following some power relationship. Secondly, I propose that the level of autonomy a subnational entity enjoys may be correlated with the size of the assembly: if a region or municipality has more autonomy, its assembly is likely to be larger. Thirdly, I propose that municipal councils that can determine their own size, will be larger, as representatives seek to ensure re-election. I test these explanations on over 600 regional assemblies in 31 OECD and EU countries and 80,000 municipalities in 31 European countries. I find that population size is the strongest predictor of council size and that the autonomy of the subnational entity is also a significant predictor and that freedom to determine assembly size is not consistently related to assembly size.