Electoral district

district, sometimes called a constituency, riding, or ward, is a geographical portion of a political unit, such as a country, state or province, city, or administrative region, created to provide the voters therein with representation in a legislature or other polity.

[1] 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, unless a non-proportional or pro-landslide election system is used such as general ticket 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 (rarely used nationwide nowadays).

But many counter-examples exist, as PR methods combined with small-sized multi-member constituencies, of DM of less than 5 for example, sometimes produces a low number of effective parties.

Droop is the mathematical minimum whereby no more can be elected than there are seats to be filled, if all the successful candidates were to receive quota.

Multiple-member contests sometimes use plurality block voting, which allows the single largest group to take all the district seats.

In the mid-19th century, John Stuart Mill endorsed proportional representation (PR) and STV precisely due to this shortcoming.

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 changes are often accompanied by redistricting, the redrawing of electoral district boundaries to accommodate the new number of representatives.

By contrast, seats in the Cantonal Council of Zürich are reapportioned in every election based on the number of votes cast in each district, which is only made possible by use of multi-member districts, and the House of Peoples of Bosnia and Herzegovina, by contrast, is apportioned without regard to population; the three major ethnic groups – Bosniaks, Serbs, and Croats – each get exactly five members.

In some places, geographical area is allowed to affect apportionment, with rural areas with sparse populations allocated more seats per elector: for example in Iceland, the Falkland Islands, Scottish islands, and (partly) in US Senate elections.

Similarly, by making four-member districts in regions where the same group has slightly less than a majority, gerrymandering politicians can still secure exactly half of the seats.

However, any possible gerrymandering that theoretically could occur would be much less effective because minority groups can still elect at least one representative if they make up a significant percentage of the population (e.g. 20–25%), compared to single-member districts where 40–49% of the voters can be essentially shut out from any representation.

[8] The district-by-district basis of 'First past the post voting' elections means that parties will usually categorise and target various districts by whether they are likely to be held with ease, or winnable by extra campaigning, or written off as a foregone loss hardly worth fighting for.

A safe seat is one that is regarded as very unlikely to be won by a rival politician based on the constituency's past voting record or polling results.

Conversely, a marginal seat or swing seat is one that could easily swing either way, and may even have changed hands frequently in recent decades - the party that currently holds it may have only won it by a slender margin and a party that wants to win it may be able to take it away from its present holder with little effort.

This may arise from a significant number of seats going to smaller regional parties instead of the larger national parties which are the main competitors at the national or state level, as was the situation in the Lok Sabha (Lower house of the Parliament of India) during the 1990s.

Elected representatives may spend much of the time serving the needs or demands of individual constituents, meaning either voters or residents of their district.

Members of the U.S. Congress (both Representatives and Senators) working in Washington, D.C., have a governmentally staffed district office to aid in constituent services.

Likewise, British MPs use their Parliamentary staffing allowance to appoint staff for constituency casework.

In some elected assemblies, some or all constituencies may group voters based on some criterion other than, or in addition to, the location they live.

Examples include: Not all democratic political systems use separate districts or other electoral subdivisions to conduct elections.