Historically, Americans have been innovators in the design of electoral systems. In its day, the Electoral College was an impressive innovation. Several vote counting methods, including Cumulative Voting, Bucklin Voting and Coombs' Method originated in the United States. Today, the U.S. is less innovative nationally, but there is much diversity in the electoral systems in use in state and local jurisdictions.
Used to elect the U.S. House Representatives, as well as many state and local legislatures, plurality is the most common and best-known electoral system currently in use in America. Under the plurality system, an area is divided into a number of geographically defined voting districts, each represented by a single elected official. Voters cast a single vote for their district’s representative, with the highest total vote-getter winning election, even if he or she has received less than half of the vote.
There are two main weaknesses in the plurality system.
First, where the boundaries of districts are drawn can have a huge effect on who is likely to win election. As a result, gerrymandering to protect incumbents or weaken political enemies is common practice under plurality rules. This is a problem inherent in any single-winner system.
Second, plurality elections are prone to the spoiler effect. Where three or more viable candidates run and split the vote within a district, the “winner” of an election can often be the candidate whom the majority of voters liked least. This characteristic of plurality elections leads to a further problem. In order to prevent the spoiler effect from negatively impacting their chances, political parties will limit the number of candidates running. This in turn leaves voters with no effective choice as elections often involve voters merely ratifying the candidate chosen by the majority party (typically at a low turnout primary) in their district.
There are other voting systems that are identical to plurality in every way, except that they use a runoff after the general election or instant runoff voting to increase the chances that the winner of an election has the support of the majority of voters. While this eliminates the spoiler effect, it does nothing to stop the negative effects of gerrymandering or the limitations inherent in making geography the primary districting criteria.
Many multi-winner systems can, however, overcome the pernicious impacts of gerrymandering -- as well as prevent the spoiler effect. They do this by (1) ensuring that geography is not the main criterion for representation and (2) assigning winners proportionally and/or based on the voters' ranking of candidates.
While single-winner districts are used in most American legislative elections, eleven state chambers and a majority of municipalities use some form of multi-winner districts. These jurisdictions include:
Historically, multi-winner districts were used to elect members of the U.S. House of Representatives and to elect most state legislators. Dan Eckam has created a neat infographic showing the use of multi-winner districts to elect each congress.
Winner-take-all is the norm in American jurisdictions, and is currently used for all national and state elections. However, proportional representation voting has been used to elect public officials in the United States since the nineteenth century. Numerous cities, including Cincinnati OH, Boulder CO, and New York City, used proportional representation--the polar opposite to winner-take-all--in the 20th century. At the state level, Illinois used multi-member districts and cumulative voting to elect their House of Representatives for over one hundred years.
Currently, voters use at-large ranked choice voting, cumulative voting, and the single vote or other forms of "limited voting" to elect city councils, school boards, and other local offices in over two hundred United States jurisdictions to achieve proportional representation in their communities. You can visit our page on proportional representation for a brief history of proportional representation voting in the United States, and the full list of jurisdictions using proportional representation voting, including what specific election method they use and when their next election will be.