A single-member district is an electoral district
represented by a single officeholder. It contrasts with a multi-member district, which is represented by multiple officeholders. Single-member districts are also sometimes called single-winner voting, winner-takes-all, or single-member constituencies.
A number of electoral system
s use single-member districts, including plurality voting
(first-past-the-post), two-round system
s, instant-runoff voting
(IRV), approval voting
, range voting
, Borda count
, and Condorcet method
s (such as the Minimax Condorcet
, Schulze method
, and Ranked Pairs
). Of these, plurality and runoff voting are the most common.
In some countries, such as Australia
, members of the lower house of parliament are elected from single-member districts; and members of the upper house are elected from multi-member districts. In some other countries like Singapore
, members of parliament can be elected from both single-member districts as well as multi-member districts.
History in U.S.
The United States Constitution
, ratified in 1789, states:
The House of Representatives shall be composed of Members chosen every second Year by the People of the several States...Representatives...shall be apportioned among the several States which may be included within this Union, according to their respective Numbers.
In other words, the Constitution specifies that each state will be apportioned a number of representatives in the House of Representatives
proportional to its population. It does not, however, specify ''how'' those representatives should be apportioned.
In the early years of the United States, a form of multi-member districts called plural district
s were the norm.
In contrast with modern proportional
multi-member districts (which had not yet been invented), plural districts were elected ''at-large
By 1842, single-member House districts had become the norm, with twenty-two states using single-member districts and only six using at-large multi-member districts. On Dec 14, 1967, single-member House districts were mandated by law (2 U.S. Code §2c
), under the justification that they served as bulwarks against southern Democrats diluting the electoral power of African Americans by using strategically drawn at-large multi-member districts (they could, for instance, create a single statewide multi-member district elected by plurality vote, all but guaranteeing the white majority would elect all Democrats).
It has been argued by proponents of single-member constituencies that it encourages a stronger connection between the representative and constituents and increases accountability and is a check on incompetence and corruption. In countries that have multi-member constituencies, it is argued that the constituency link is lost. For example, in Israel the whole country is a single constituency and representatives are selected by party-lists.
On the other hand, today most voters tend to vote for a candidate because they are endorsed by a particular political party or because they are in favour of who would become or remain the leader of the government, more than their feelings for or against the actual candidate standing. Sometimes voters are in favor of a political party but do not like specific candidates. For example, voters in Canada re-elected the Alberta
government in 1989 but, because of dissatisfaction with its leadership, the premier and leader of the governing party, Don Getty
, lost his seat.
Fewer minority parties
It has been argued that single-member districts tend to promote two-party system
s (with some regional parties). Called Duverger's law
, this principle has also been empirically supported by the cube rule
, which shows how the winning party in a first-past-the-post
system is mathematically over-represented in the final chamber of representatives.
Supporters view this effect as beneficial, claiming that two-party systems are more stable, and that the minority opposition does not have undue power to break a coalition. First-past-the-post minimizes the influence of third parties and thus arguably keeps out opposition. Critics of two-party systems believe that two-party systems offer less choice to voters, create an exaggerated emphasis on issues that dominate more marginal seats, and does not completely remove the possibility of a balanced chamber (or hung parliament
), which can also give undue power to independents and lead to more, not less, stability.
A safe seat is one in which a plurality or majority of voters, depending on the electoral system, support a particular candidate or party so strongly that the candidate's election is practically guaranteed in advance of the vote. This means all other voters in the constituency make no difference to the result. This results in feelings of disenfranchisement and nonparticipation
by some voters, both supporters of the dominant candidate (who can safely abstain from voting because their preferred candidate's victory is assured) as well as his or her detractors (who know their preferred candidate is guaranteed to lose).
Single-member districts enable gerrymandering, the practice of manipulating district boundaries to favor one political party. Whereas proportional multi-member districts ensure that political parties are represented roughly in proportion to the share of the vote they receive, in single-member districts the entire district is represented by a single political party, even if a sizeable minority of the electorate voted for another party. This enables political parties to rig elections in their favor by drawing districts in such a way that more districts are won by their party than their proportion of the overall vote would dictate (in the 2018 Wisconsin State Assembly election
, for example, the Republican Party
won 45% of the popular vote but 64% of the seats).
Comparison of single-member district election methods
* Duverger's law