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Ranked Choice Voting — New York City 2021 Mayoral Primary

New York City Board of Elections / Common Cause / Rank the Vote NYC · New York City, USA · 2021

Summary

New York City's 2021 ranked-choice voting rollout was the largest US municipal implementation of RCV to date and the most demographically diverse natural experiment available for studying how the mechanism performs in a large urban electorate. Pre-adoption critics argued that RCV would confuse voters of color, increase ballot exhaustion, and produce winners with weaker mandates. The empirical evidence broadly contradicted these predictions: ranking behavior was high (84% used multiple ranks), demographic gaps in usage were smaller than anticipated, and the winning candidate emerged with a genuine majority. Important caveats remain: ballot exhaustion (14%) was non-trivial, the initial vote-count error by the NYC Board of Elections undermined public confidence, and longer-term effects on campaign behavior, voter turnout, and policy outcomes are still being studied. The NYC implementation is now the largest existing evidence base on RCV in diverse urban populations, and is being heavily cited in the growing debate over state-level adoption (Maine, Alaska, and proposals in Massachusetts, Colorado, and Nevada). What makes it a particularly clean natural experiment is that the mechanism change was identifiable and discrete, the comparison data (prior plurality primaries) is rich, and the demographic stratification of New York City allows credible subgroup analysis.

Research question

"Does ranked choice voting (RCV) in a large urban primary election reduce ballot exhaustion, change the demographic profile of who wins, alter campaign behavior, and produce winners with broader majority support — and do voters understand and use the ranking system effectively?"

Methodology

Intervention

New York City implemented ranked-choice voting for the first time in its 2021 primary elections for mayor, public advocate, comptroller, borough president, and City Council. Voters could rank up to five candidates in order of preference. If no candidate received a majority of first-choice votes, the candidate with the fewest votes was eliminated and their supporters' next-choice votes were redistributed, repeating until a majority winner emerged.

Assignment

Natural experiment — first use of RCV in NYC; comparison to prior plurality primaries and to demographic ballot data analyzing voter use of ranking, exhausted ballots, and tabulation rounds

Sample size

Approximately 940,000 ballots cast in the Democratic mayoral primary; analysis of ballot data from all five borough president and dozens of city council races

Primary outcome

Ballot exhaustion rate (% of ballots that didn't count toward the final round); demographic differentials in ranking behavior; campaign-conduct measures (negative ads, candidate cross-endorsements); voter satisfaction and understanding

Effect estimate

Ballot exhaustion was approximately 14% in the final mayoral round; 84% of voters ranked multiple candidates; demographic gaps in ranking behavior were smaller than predicted (Black, Latino, and Asian voters used the full ranking similarly to white voters); winning candidates secured genuine majority coalitions rather than plurality wins. Eric Adams won with 50.4% in the eighth round.

Decision

NYC continues to use RCV for municipal primaries. The 2021 implementation surfaced operational issues (initial vote-count error by NYC BOE) but the underlying RCV mechanism was upheld and refined. Subsequent ranked-choice implementations in Alaska (2022) and growing US adoption draw partly on the NYC evidence base.

Result

Mixed

Ballot exhaustion was approximately 14% in the final mayoral round; 84% of voters ranked multiple candidates; demographic gaps in ranking behavior were smaller than predicted (Black, Latino, and Asian voters used the full ranking similarly to white voters); winning candidates secured genuine majority coalitions rather than plurality wins. Eric Adams won with 50.4% in the eighth round.

Evidence strength

Limited

Observational or pre-post design; correlation not necessarily causal.

Replication status

Open for replication

Institution

New York City Board of Elections / Common Cause / Rank the Vote NYC

Location

New York City, USA

Year

2021

Policy area

Voter Engagement

Mechanism

Default

Other trials of this mechanism

Cite this entry

New York City Board of Elections / Common Cause / Rank the Vote NYC. (2021). Ranked Choice Voting — New York City 2021 Mayoral Primary. The Experiment Society Registry. Retrieved from https://www.experimentsociety.org/registry/ranked-choice-voting-nyc-2021 (primary report: https://www.commoncause.org/wp-content/uploads/2022/03/Ranked-Choice-Voting-Voter-Behavior-NYC-2021.pdf)

Citation network

Cited by 1 other entry in the registry

Cross-references

Adjacent experiments — same domain, parallel pilots, or alternative mechanisms.

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Open for replication

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