Does prepaid postage increase voter turnout? An analysis across time and municipalities in Switzerland

Abstract

Political participation is the backbone of democracy. One measure to increase voter turnout in vote-by-mail systems is prepaying postage. Previous studies investigated the effect of prepaid postage and found that it significantly increases turnout. Using an original data set covering all national direct democratic votes in 1893 Swiss municipalities from 2005 to 2023, we replicate earlier studies and investigate temporal as well as contextual variation. We find that the effect of prepaid postage on turnout is contingent upon both time and municipal characteristics: 1) postage starts to increase turnout only after three to five years. 2) Abolishing prepaid postage reverses the increase in turnout. 3) The effect is larger in municipalities with more post boxes and a greater average distance to the office of municipal authorities. The evidence from our study suggests that prepaid postage cannot be viewed as a one-size-fits-all solution.