The effect of district magnitude on turnout: Quasi-experimental evidence from nonpartisan elections under SNTV

The relationship between district magnitude and turnout remains hotly debated, and previous studies suggest positive, negative, and nonlinear effects depending on other institutional characteristics. This article contributes to the empirical literature by conducting a quasi-experimental test on the effect of district magnitude in a context of a single nontransferable vote (SNTV) system with weak partisan ties: municipal council elections in Japan. Exploiting a credible source of exogenous variation in district magnitude and using a fuzzy regression discontinuity design, we reveal that a 5-seat increase in an average-magnitude district reduces turnout by 4 percentage points, which accounts for a 6.9% drop in the size of the electorate. We reason that, in the context of SNTV with weak parties, higher district magnitude leads to information overload, which may lower voters’ incentives to turn out.