An overvote occurs when a voter selects more options than a contest permits — for example, marking two candidates in a single-winner race, or marking more than the maximum number of candidates in a multi-seat at-large race. Under nearly all jurisdictions' rules, an overvoted contest is rejected and recorded as a "no vote" for that race, although other contests on the same ballot remain valid.
Overvotes are distinguished from undervotes, which occur when a voter selects fewer options than permitted (including leaving the contest blank). Together, overvotes and undervotes are referred to as residual votes, a metric election scientists use to compare the accuracy of voting technologies.
The concept became politically prominent during the 2000 U.S. presidential election in Florida, where punch-card and optical-scan ballots produced large numbers of overvotes — particularly on the controversial "butterfly ballot" in Palm Beach County, where the layout led some voters to punch holes for two presidential candidates. Post-election studies, including the 2001 National Opinion Research Center (NORC) Florida ballot review commissioned by a media consortium, examined how overvotes and undervotes might have changed the outcome had different counting standards been applied.
In response, the U.S. Congress passed the Help America Vote Act (HAVA) of 2002, which in Section 301 requires voting systems used in federal elections to notify the voter of an overvote and give them an opportunity to correct the ballot before it is cast — a feature known as second-chance voting. Precinct-count optical scanners and most DREs comply with this requirement; central-count systems generally do not, which is one reason vote-by-mail ballots historically have higher overvote rates.
In ranked-choice voting (RCV), rules vary: many jurisdictions treat an overvote at a given ranking as exhausting the ballot from that point forward, while skipped rankings are typically ignored. Election administrators track overvote rates as a quality-control indicator for ballot design and voter education.
Example
In Palm Beach County, Florida during the November 2000 presidential election, roughly 19,000 ballots were discarded as overvotes after voters marked both Al Gore and another candidate on the butterfly ballot.
Frequently asked questions
An overvote selects more candidates than allowed in a contest; an undervote selects fewer (including leaving it blank). Both are forms of residual votes.
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