Single Member Plurality Systems

Voters in a single member plurality election cast a vote for one candidate. The candidate receiving the most votes wins. While this is the most commonly used voting system in the United States, it presents both advantages and disadvantages.

The single member plurality voting system (SMP) is the most commonly used voting system in the United States. SMP works with single-member districts, meaning geographically-defined districts that send one representative to a legislature. Voters in a given district cast one vote for their favorite candidate, and the candidate receiving the most votes is elected. This system commonly works in a series of two elections, in which primaries are held to determine a nominee from each major party, followed by a general election that pits the primary winners against one another.

Of the 211 democratic nations of the world, 68 -- including the United States and most other former British countries -- use SMP as their principal electoral system (The International IDEA Handbook of Electoral Design, p. 20-21). Of major, full-fledged democracies, however, very few use SMP. Canada and the United States are the only nations regularly appearing on the list of democracies with at least two million countries and a high human rights rating from the organization Freedom House that do not use a form of proportional representation for one of their national elections.

Supporters of SMP tout the strong local representation afforded by single-member districts, as every representative represents and speaks for the people of a particular district. Furthermore, supporters argue, SMP tends to reinforce one-party government in a legislature and a two-party system, which they maintain leads toward greater accountability and more efficient government (see factsheet __). Supporters also note that voters easily understand SMP.

Nevertheless, the majority of democracies have turned away from SMP. Critics make many arguments against SMP. [See Factsheet for a more detailed analysis of the problems with SMP systems]. Among them are:

Democracy in the United States of course has much to say for it, despite these drawbacks. Some argue that these positive aspects are less due to SMP than to other factors, including a strong and independent judiciary, a free press, an active citizenry, federalism and checks and balances within federal and state government.

This factsheet is part of the CVD Factbook Series, a compilation of one-page factsheets covering voting systems and voting system reforms.