Cambridge, Massachusetts uses choice voting, also known as STV or the single transferable vote to elect its city government and school board. This voting system is a non-winner-takes-all method of proportional representation, which allows all groups to win fair representation in proportion to their share of the population. Cambridge holds the distinction of being the only jurisdiction in the United States that still uses a choice voting system. Choice voting in Cambridge has survived legal challenges, most recently in 1996. The Supreme Court of Massachusetts deemed choice voting to be constitutionally valid. There have also been 5 failed referenda to repeal choice voting.
Cambridge, MA adopted choice voting in 1941, in an effort to increase African-American representation in local government. Since its inception, the African American community of Cambridge has been able to elect representatives to both bodies in almost every election in the 1960’s and 1970’s – with between 5-10% of the total population.
Contrary to what some critics have speculated, choice voting has not proved too complicated for voters. In Cambridge, the elections have an average of 2% error rate. This figure includes both incorrectly marked ballots and blank ballots where the voter may have only participated in a higher-level election. In the future, to further reduce this error rate, Cambridge could allow error correction for the voters.
To count the votes, "winning threshold" (the minimum number of votes need to win a seat) is calculated, and used to determine winners. Votes candidates achieve above the threshold are transferred to help other candidates, and candidates with little support are eliminated, and their votes transferred to more viable candidates, ensuring that as many voters as possible have some say in who wins election.