Effect of Malapportionment on Voter Turnout: Evidence from Japan's Upper House Elections

Malapportionment is a widely used tool of electoral manipulation in both authoritarian and democratic countries. Although its impact on electoral and policy outcomes has received considerable scholarly attention, the impact of malapportionment on electoral participation has been neglected. This is partly because it is difficult to isolate the effect of malapportionment on electoral participation from that of other factors. To the best of my knowledge, this study is the first to examine the effect of malapportionment on electoral participation. I avoid the methodological problem by taking advantage of the unique characteristics of Japan's upper house election laws. Using an original dataset on Japan's upper house elections and employing a differences-in-differences design, my results show that malapportionment increases voter turnout (by an average of 2.9 percentage points and up to 8.0 percentage points). This study therefore contributes to the literature on election laws and political participation by providing strong evidence for the effect of malapportionment on voter turnout and showing that some forms of electoral manipulation can increase voter turnout.