Electoral Systems 101

1870s ballot boxElectoral Systems 101

The two main families of electoral methods are known as proportional representation and winner-take-all. Under proportional representation, parties or factions gain seats in proportion to the number of voters who voted for them. Winner-take-all methods, by contrast, allow a single majority group to control all seats. 

Elections which elect one winner, such as senator or president, are, by definition, winner-take-all. Elections which elect multiple winners, like city council or state legislative elections, can be proportional or winner-take all.

Single-winner vs. multi-winner systems

Sometimes, electing only one person makes sense — as when nations elect presidents or cities elect mayors. However, the calculus changes when electing legislative bodies. The choice between single- and multi-winner systems has profound consequences.

Multi-winner districts are associated with: 

Common multi-winner systems include block voting, list proportional representation, multi-member proportional representation, and proportional ranked choice voting.

 Single-winner districts are associated with: 

Common single-winner systems include plurality voting, two-round runoffs, and ranked choice voting

Proportional representation vs. winner-take-all

In legislative elections, lawmakers can be elected proportionally or by “winner-take-all.” 

In proportional representation, like-minded groups of winners are allocated in alignment with the share of votes they receive. In a five-winner district, for example, a political party that received 38% of the vote would elect two candidates and a party that received 62% of the vote would elect three. 

Winner-take-all, by contrast, operates on the principle that the candidate(s) with the most votes win. Consequently some voters are represented and others are not. In a five-winner district, for example, a single party (or candidate) can win all five seats, even if only a slim majority of voters support that party or candidate. This sort of outcome was common in early congressional elections, when many states elected their state legislatures using winner-take-all voting methods in multi-member districts. Winner-take-all election methods are often targeted under the Voting Rights Act because they can dilute the power of minority communities to elect candidates of their choice. Learn more about the Voting Rights Act here.

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