Single-winner voting systems

A single-member district or single-member constituency is an electoral district that returns one officeholder to a body with multiple members such as a legislature. This is also sometimes called single-winner voting or winner takes all. The alternative are multi-member districts, or the election of a body by the whole electorate voting as one constituency.

A number of electoral systems use single-member districts, including plurality voting (first past the post), two-round systems, instant-runoff voting (IRV), approval voting, range voting, Borda count, and Condorcet methods (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 and India, 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 that are headed by members of the Cabinet.

Single-member House districts became law on Dec 14, 1967.2 U.S. Code §2c

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.

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