Studies of a small number of countries have revealed that both democratic and non-democratic subnational governments can exist within a single country. However, these works have neither demonstrated how common subnational regime variation is nor explained why some countries are more prone to it. This paper does both. Using Varieties of Democracy subnational data for countries of the world from 1900 to 2012, we show that subnational regime variation exists throughout all regions, in both unitary and federal states, and in both the present and past. The paper also demonstrates theoretically and empirically how social heterogeneity and factors undermining the national government’s ability to broadcast power promote this variation. Specifically, subnational regime variation is more common in countries that are ethnically and economically diverse, rugged, and populous. These measures, our theory, and the benchmark models we developed will spur new research in regime types and change.
Kelly McMann, John Gerring, Matthew Maguire, Michael Coppedge, and Staffan Lindberg. "Governing Countries: A Theory of Subnational Regime Variation" University of Gothenburg, Varieties of Democracy Institute: Working Paper No. 28 (2016).