Spanish local elections provided a natural experiment to compare voter turnout under different systems.

Electoral Systems Compared

• System 1: Closed list proportional representation
• System 2: Open list, plurality-at-large system allowing candidate votes

Using regression discontinuity design based on municipal population size thresholds mandated by national law:

Key Findings

• The open list system increased turnout by approximately 1-2 percentage points compared to closed lists.
• This competitive structure within and across parties appears directly linked to higher participation rates.

Real-World Significance

This suggests electoral reforms favoring open PR systems could significantly boost democratic engagement in Spain.