District magnitude refers to the number of seats assigned to each district, and in conjunction with number of districts, determines the number of district seats to be filled in an election. Staggered terms are sometimes used to reduce the number of seats up for election at any one time, when district magnitude is more than one. The term was first used by the American political scientist
Douglas W. Rae in his 1967
dissertation The Political Consequences of Electoral Laws. The district magnitude affects the ease or difficulty to be elected, as the effective threshold, or
de facto threshold, decreases in proportion as the district magnitude increases in multi-member districts and
plural districts, unless a non-
proportional or landslide-prone election system is used such as general ticket voting and
plurality block voting. Where multi-member districts are used, threshold
de facto stays high if seats are filled by
general ticket or other pro-landslide party block system, although this is rarely used nationwide. Duverger drew a correlation between proportional representation and multi-party systems (
fragmentation). The results of different district magnitudes supports
Duverger's observation that single-winner contests tend to produce
two-party systems, and
proportional representation (PR) methods tend to produce
multi-party systems, although even first past the post election systems, such as Canada's, can produce multi-party legislatures. Also some PR systems when used in small-sized multi-member constituencies, of DM of less than 5 for example, sometimes produce a small
number of effective parties. Malta diverges from Duverger's rule. It uses DM-5 districts and has a two-party system. Meanwhile, systems that use
first-past-the-post system election system sometimes elect members of five different parties due to local conditions in the multitude of separate micro-battles across a country, as we see in Canada and several other countries) Contests with district magnitude of 1 mostly use plurality voting in
single-member districts (first-past-the-post voting) but
instant-runoff voting or the
two-round system is used in other cases. In both systems each voter has one vote in the round of voting. District magnitude is larger than 1 where multiple members are elected (
plural districts), and such districts have available a wide variety of election methods. Such districts usually use one of these systems:
plurality block voting (where voter may cast as many votes as the number of seats to be filled), list
proportional representation,
single transferable vote elections (where each voter casts just one transferable vote).
Limited voting and
single non-transferable vote are used less often. In other cases, each seat in the multi-seat district is filled through a separate contest, usually through
first past the post. In list PR systems district magnitude may exceed 100, but in many cases the average district magnitude under list PR is only about 14. In elections under single transferable vote systems, district magnitude normally ranges from 2 to 10 members in a district. Sometimes STV uses a greater district magnitude than that. Examples are at-large
optional preferential elections in
New South Wales Legislative Council (district magnitude of 21) and the 2025
Western Australian Legislative Council (district magnitude of 37). District magnitude is maximized where: • jurisdictions with a single electoral district for the whole elected body (at-large voting). This includes the legislatures of:
the Netherlands (1 district for population 13 million and 150 seats),
Serbia (7 million, 250 seats),
Israel (10 million, 120 seats),
Slovakia (4 million, 150 seats), and
Moldova (3 million, 101 seats). In each of these cases, it takes less than a percentage point of the nation's electorate to capture a seat. • systems use a two-tier form of
party-list proportional representation, using both local multi-member constituencies (of various district magnitudes and seat-to-vote ratios), and national
levelling seats where parties' nationwide vote tallies have priority (Mixed-Member Proportional). That is the case in Scandinavia:
Sweden (population 6.5 million, 349 seats, 29 districts, see
national apportionment of MP seats in the Riksdag article),
Denmark (4 million, 179 seats, 12 districts),
Norway (4 million, 169 seats, 19 districts), and
Iceland (0.2 million, 63 seats, six districts). • systems use a two-tier form of
party-list proportional representation, using both local single-member districts, and national
levelling seats, when the parties' nationwide vote tallies have priority (Mixed-Member Proportional). New Zealand uses such an MMP system. • systems use a three-tier form of
party-list proportional representation, using both local single-member districts, and state and national levelling seats, to produce proportional representation in each state and nationwide based on party votes cast by voters (Mixed-Member Proportional). From 2017 to 2023, Germany's
Bundestag also allocated
additional members to make up for
overhang seat won by parties and allowed parties to win single-member-district seats even if not proportionally due them. After 2023, a party is allowed to take only as many seats as its proportion of the second vote (party vote) allows. If it elects too many single-member-district seats, they are disallowed, and allocated to another party. DM is moderate where districts break up the electorate or where relatively few members overall are elected, even if the election is held at-large. District magnitude may be set at an equal number of seats in each district. Examples include: all districts of the
Northern Ireland Assembly elect 5 members (6 members prior to 2017); all those of the
Parliament of Malta elect 5 MPs; all those of the Welsh Assembly elect 6. Chile, between 1989 and 2013, used a method called
binomial voting, which assigned 2 MPs to each district. In many cases, however, multi-member constituencies correspond to already existing jurisdictions (regions, districts, wards, cities, counties, states or provinces), which creates differences in district magnitude from district to district: •
Republic of Ireland for the
Dáil Éireann: 3-, 4-, and 5-member districts. (STV is used) •
Hong Kong for half of the
Legislative Council of Hong Kong: 5- to 9-member districts. • The
New Hampshire House of Representatives: 1- to 10-member districts (
Plurality block voting is used). •
South Africa 27 million registered voters and 400 seats (with 200 filled in nine provincial-wide districts using party lists, and 200 elected according to PR. Provincial representation in the National Assembly, elected in province-wide districts, ranges from 5 seats in the Northern Cape to 48 seats in Gauteng. Where districts have the same vote-to-member ratio, the number of votes needed to be elected are very similar district to district, irrespective of the district magnitude in the district. Proportional representation in a district elects multiple members who represent a variety of opinion, and therefore relatively few votes are wasted. Where the intent is to avoid the waste of votes, transferable ranked votes are used in addition to the election of multiple members. A quota, a set proportion of votes as a minimum, assures the election of a candidate and allows surplus votes to go to where they might be useful. In such elections, a large proportion of votes are used to elect someone. The quota is often set as the inverse of the district magnitude plus one, plus one, the
Droop quota. Droop is the mathematical minimum whereby no more can achieve quota than there are seats to be filled, if all the successful candidates were to receive quota. Such calculation is rendered un-necessary if even one vote is exhausted or rejected during the count process. In a STV contest, a candidate that accrues Droop quota is certain of being elected. STV is intended to avoid waste of votes as much as possible by the use of transferable votes. If the STV rules permit voters not to rank all the candidates or prevent them from ranking all the candidates, some votes are found to be exhausted, so votes are not transferred even if the candidate is elected or declared defeated or un-electable. Thus it is common for one or two members in a district to be elected without attaining Droop, but still they are seen to be the most-popular at that point in the count. Where party list PR is used, the Hare quota (the natural
electoral threshold) is often used. For instance, in a system that uses party vote tallies to allocate seats, a party with ten percent of the vote will win a seat in a 10-member district as its 10 percent of the vote means it is due one seat of the ten. Thus, a threshold of ten percent in a ten-seat district is equivalent to a
Hare quota. That same party will not win a seat in a 5-member district. In systems where a noticeable number of votes are wasted, such as Single non-transferable voting or
first past the post voting, or Instant-runoff voting, especially if voters are prohibited from ranking all candidates, candidates may win with less than Hare or even Droop. Larger district magnitudes means larger districts, so reduces
gerrymandering. Gerrymandering is the practice of partisan redistricting by means of creating imbalances in the make-up of the district map, made easier by a multitude of micro-small districts. A larger district magnitude also means fewer wasted votes. As well, a fair voting system in the district contests also means that gerrymandering is ineffective because each party gets its fair share of seats however districts are drawn, at least theoretically. Multiple-member contests sometimes use
plurality block voting, which allows the single largest group to take all the district seats. Each voter having just one vote in a multi-member district, Single voting, a component of most
party-list proportional representation methods as well as
single non-transferable vote and
single transferable vote, prevents such a landslide.
Minorities Large district magnitude assists in the inclusion of
minorities. Single-winner plurality elections (and other elections with lower district magnitudes) are known to limit the representation of minorities. In the mid-19th century,
John Stuart Mill endorsed
proportional representation (PR) and STV precisely due to this shortcoming. In systems with smaller district magnitudes, various mechanisms have been employed to enhance the representation of demographic minorities. For example, gender quotas are used in some jurisdictions to ensure a minimum level of female representation. These quotas may require political parties to nominate a certain proportion of women candidates in
single-member districts, or to structure
party lists in a "zippered" or gender-balanced manner in multi-member districts. Such quotas can be mandated by law or adopted voluntarily by political parties, as in the case of the
UK Labour Party, which has implemented
all-women shortlists since 1995. Ethnic minority representation is also addressed through institutional design in several countries. In
Singapore, the
Group Representation Constituency system mandates that each electoral team includes at least one member from a minority racial group. In the
United States, the Supreme Court has interpreted the
Voting Rights Act to require the creation of
minority-majority districts where feasible, ensuring that minority populations have a fair opportunity to elect representatives of their choice. This requirement is implicit and arises from judicial interpretations of anti-discrimination principles in electoral zoning. In
New Zealand,
Māori electorates have existed since the 19th century, allowing voters of Māori descent to elect their own representatives. Unlike the U.S. system, these electorates explicitly distinguish between ethnic groups and often overlap with general electorates. Large district magnitudes increase the chance for diverse walks of life and minority groups to be elected. However, it is not synonymous with proportional representation. If a district allocates seats based on "general ticket voting", it prevents the district's multiple members from being mixed and balanced. Where list PR is used in the district, a
closed list PR method gives the party machine, not the voters, the power to arrange the candidates on the party list. In this case, a large district magnitude helps minorities only if the party machine of any party chooses to include them or if the minority group has its own party. In a multi-member district where general ticket voting is not used, there is a natural impetus for a party to open itself to minority voters, if they have enough numbers to be significant, due to the competitive environment produced by the electoral system. ==Apportionment and redistricting==