New York City has a long history of proportional representation, also known as choice voting, dating back to the 1930s and 1940s where it was used for City Council elections. New York City was one of 23 cities across the country to use proportional representation (PR). It was very successful in acheiving the promise of increased diversity. Adam Clayton Powell was the first African-American elected to the New York City Council and it was under this system.
Several members of third parties of the time were also elected, including the American Labor Party, the Communist Party and the Fusion Party. Unfortunately, a "red scare" campaign was lauched to overturn PR in the '40s and it succeeded.
FairVote Reviews Potential for Choice Voting for New York City
Lynne Serpe to assess and explore options for NYC