An electoral system in which seats in a legislature are awarded to each party on the basis of its share of the popular vote. The United States does not use a system of proportional representation. Membership in the Senate and the House of Representatives, for example, is based on individual candidates' receiving a majority of votes. Such a system strongly encourages the formation of only two major political parties.

Note: In Israel and some nations in Europe, a system of proportional representation guarantees that small parties will have official recognition in the government, thus leading to a multiparty government.

Note: Though proportional representation has been attempted in a few American cities, many American politicians argue that it tends to fragment the government, preventing quick and decisive action.