IRV and Proportional Voting

The most prevalent system for legislative elections in the United States is the winner-take-all, single-member district plurality system.  Under this system, votes are cast in single-member districts—districts in which only one member of the legislature is elected. All the candidates are on the ballot and a voter casts a vote for only one of them.  The winner is determined by who receives the most votes—the plurality of the vote. This voting system is so familiar to people in the United States that we hardly ever stop to think about it.  Many voters assume this is how democratic elections work.

But there are other kinds of democratic voting systems. The main alternative to the single-member plurality system is proportional representation or PR.  Almost every democracy outside of Britain, Canada and the United States uses some version of proportional voting, including Australia, Germany, Japan, New Zealand and South Africa. The new voting systems in Afghanistan and Iraq are proportional too.

Various PR systems use different ballots and different ways of counting votes, said Prof. Mebane, “But all PR systems have two things in common. First, proportional representation voting systems elect people in multimember districts. Instead of one member of the legislature being elected in a small district, PR uses larger districts where five, ten, or more members are elected. So instead of only one winner, there are multiple winners in each district. Secondly, PR systems distribute the seats according to the proportion of the vote won by particular parties or political groups. For example, in a ten-member PR district in which the Democratic candidates won 50% of the vote, they would receive five of the ten seats. With 30% of the vote, the Republicans would win three seats, and if a third party like the Green party or the Libertarian party won 20% of the vote, that party would get the remaining two seats.

PR voting systems have a number of benefits. For example, winner-take-all systems make it very difficult for racial and ethnic minorities and women to win their fair share of seats.  PR is explicitly designed to ensure fair representation for these groups.  Though the vote has since been extended to all Americans, Congress has, for the most part, remained a club of prosperous white men. Of one hundred senators, only eight are women and one African-American; of 435 representatives, 48 (11 percent) are women and 38 (9 percent) African-American. Only in the case of African-Americans in the House of Representatives does the proportion come close to reflecting reality. And this has been achieved only by drawing strange-looking districts that create artificial majorities at the expense of new minorities.

Healey noted that PR virtually eliminates the swing factor, that often small percentage of the vote that tilts an election one way or the other under winner-take-all. In so doing, it addresses two of the scourges of American politics: gerrymandering and the influence of money.

Single member districts encourage gerrymandering — the manipulation of district lines to unfairly benefit certain candidates or parties. If a swing vote of 5 percent can be leveraged into a 100 percent change in the outcome of an election, it pays to manipulate district boundaries or concentrate campaign funds on close races. With proportional representation, these efforts are far less rewarding.

Increased voter turnout is another benefit of PR. Americans have the lowest participation rates in the developed world precisely because many voters are denied a meaningful choice.  Voter turnout is generally estimated to be 10-12 percent higher in nations with PR than in similar nations using winner-take-all elections.

Instant runoff voting or IRV is used to elect single member offices such as mayor or district attorney.   IRV ensures that the winning candidate receives the support of the majority of voters.  That is not always the case in plurality voting.  Assume for instance that there are three candidates vying for office and the Republican receives 43% of the vote, the Democrat receives 40% and the Green candidate 17%. Under plurality rules, the Republican wins — even though the majority of voters opposed that candidate and voted other candidates.   This example illustrates another problem of plurality voting: the spoiler.   A spoiler is a minor party candidate who takes away enough votes from one major party candidates to ensure the election of the other major party candidate, who would not have won otherwise.  In the example above, those who voted for the Green candidate inadvertently helped the Republican candidate win.

IRV eliminates both minority winners and spoilers.  In the above example, since neither major party candidate received over 50% of the vote, the weakest candidate— the Green Party candidate— would be eliminated and his or her votes transferred to their second choices.  Assuming 11% of the Green vote goes to the Democrat, that candidate would win with 51% of the vote.   In this way, IRV ensures a winner supported by the majority of voters, and also that votes for minor party candidates do not inadvertently aid in the election of a candidates those voters want the least.

IRV has become a popular election reform around the country in recent years. It is used for local elections in San Francisco and Burlington (VT) and for overseas military voters in South Carolina, Arkansas and Louisiana. Minneapolis, Oakland and a number of cities and counties in North Carolina are all in the process of implementing IRV for use in the next few years. Colorado recently became the first state to use IRV to fill a vacancy in the state legislature. Takoma Park, Md., will use IRV for the first time in 2007 to elect the mayor and city council. Minneapolis voted to use instant runoff balloting for City Council and mayor starting in 2009 and proportional voting for park and library boards.



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