Graphs · Across offices

Descriptive views of the CPLD across four elected offices — the Chamber of Deputies, mayors, municipal councils, and regional councils — from 1989 to 2025. Every figure is computed directly from CPLD v3.0, aggregated by election.

Chamber of Deputies · Diputados

Fragmentation: votes vs. seats

ENPv & ENPs, national · Laakso–Taagepera · 1989–2025

Effective number of parties by vote (ENPv) and by seat (ENPs). Both stayed near 2–2.5 through the binomial era, then jumped after the 2015 reform (first applied 2017, dashed line). Votes now fragment faster than seats.

Ideological polarization

Dalton index, national · 1989–2025

Ideological polarization (Dalton index). Unlike fragmentation, polarization began climbing in 2009 — before the reform — and has risen nearly every cycle since, reaching its highest recorded level in 2025.

Mayors · Alcaldes

The rise of independents

share of independent mayoral candidates (%) · 2004–2024

Independents as a share of mayoral candidates. After holding near 20% for over a decade, independents have surged to 39% in 2024 — roughly two in five mayoral candidates now run with no party.

Municipal councils · Concejales

Council fragmentation

effective number of parties (ENPv) · 2004–2024

Effective number of parties on municipal councils. Proportional rules let fragmentation run further than anywhere in the legislature — from ~2.4 in 2004 to a peak of 9.7 in 2021.

Regional councils · Cores

The candidate explosion

mean candidates per district · 2013–2024

Average candidates per regional-council district. The young office (created 2013) more than doubled its field by 2021, when districts averaged 45 candidates each.

All offices

Effective number of parties, by office

ENPv, national · 2021 elections

Effective number of parties across every office in the 2021 cycle. Proportional, multi-member bodies (blue) fragment far more than single-winner executive races (grey): regional councils topped twelve effective parties, while mayors and governors stayed below five.

Ideological polarization, by office

Dalton index, national · most recent cycle (2023–25)

Ideological polarization in each office's most recent election. Polarization is now high and strikingly uniform across every level of government — a system-wide shift, not confined to the legislature.