Family of electoral formulas that allocate legislative seats to parties in proportion to the share of the vote each receives, in contrast to the winner-take-all logic of a plurality system. Seats are distributed across multi-member constituencies, or in some systems a single nationwide constituency, using a formula such as the D'Hondt method, devised by the Belgian mathematician and jurist Victor D'Hondt and first described in 1878, or the Sainte-Lague method. Belgium became the first country to hold a national parliamentary election under proportional representation, on 27 May 1900, after the D'Hondt-based reform became law on 29 December 1899, replacing single-member constituencies with multi-member ones typically electing between three and eighteen members; that 1899 reform is the origin year this atlas records for the mechanism, a first national adoption rather than a first proposal. The system spread across continental Europe in the following decades and today underlies most legislatures of the European Union and much of Latin America. Because a proportional formula lets smaller parties win seats in rough proportion to their support rather than being shut out entirely, it tends toward multi-party legislatures in which no single party wins a majority outright, an effect formalized as Duverger's law and one directly reflected in proportional representation's well documented tendency to produce coalition government. The single transferable vote is one specific method of achieving proportionality, using ranked ballots in multi-member districts rather than party lists.
Facts
Origin YearFirst NATIONAL parliamentary election under proportional representation: Belgium, 27 May 1900, after the D'Hondt-based reform became law on 29 December 1899. Not a first-proposal date; D'Hondt himself described his method in 1878, and earlier proportional schemes exist. Carried forward unchanged from the ideology-type entity this replaces (198). Founding ContextDeveloped across the late nineteenth and early twentieth centuries as legislatures sought to translate a party's share of the vote more closely into its share of seats than single-member plurality systems allow; Belgium adopted the first national party-list system in 1899, following advocacy by mathematician Victor D'Hondt. 1 Cross-Tradition Connections
Associated With
Italy, Countries Italy is named among PR-using countries and discussed further in the article's trends section.
Russia, Countries Britannica names Russia among the countries using proportional representation.
The UK adopted PR for European Parliament elections and some local elections in London and Northern Ireland.
Encompasses
STV is one specific method, ranked ballots counted by quota and surplus transfer in multi-member districts, of achieving the same proportional outcome party-list systems pursue by a different formula.
Influenced
The observed tendency of proportional systems toward multiple viable parties is the other half of the empirical pattern Duverger's law generalizes.
Sources
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