Single-member district

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, single-member constituencies or single-member electorates. 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, while members of the upper house are elected from multi-member districts. In some other countries, such as Singapore, members of parliament can be elected from both single-member districts as well as multi-member districts. 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 districts were the norm. In contrast with modern proportional multi-member districts (which had not yet been invented), plural districts were elected at-large in plurality votes. 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.