A strong majority of Westbrook voters decided Tuesday that ranked-choice voting will be expanded to municipal elections.

The vote was 2,819-1,660, with 63 percent of voters supporting a measure that sprang from a grassroots effort and reflects a growing national interest in the alternative voting method.

The City Council voted 5-0 to put the proposed charter amendment on the ballot after a small group of citizens held a successful petition drive to extend ranked-choice voting beyond certain state and federal elections, where it already happens under state law.

“I just think we should have ranked-choice voting at all levels,” petition leader Samantha Bassett said.

As a result of Tuesday’s vote, Westbrook will become the second city in Maine – following Portland – to use ranked-choice voting in municipal elections, including  mayoral, City Council and school committee races.

Sometimes called instant-runoff voting, the method allows voters to rank candidates in order of preference, by marking first, second and subsequent choices. Voters are not required to rank candidates. If no candidate in a race receives more than 50 percent of the vote in the first tabulation, ballots are recounted in successive rounds to eliminate the lowest-ranked candidates until one candidate receives a clear majority exceeding 50 percent. Tabulation is done by computer with paper ballots as backup.

Westbrook’s effort reflects growing national interest in ranked-choice voting, which gained traction in 2016 when Maine voters approved the voting method in a referendum that won 52 percent of the vote. After overcoming many legal and logistical challenges, Maine finally enacted the measure in 2018. It remains the only state to fully implement ranked-choice voting, which it uses for state and federal primaries, and federal elections, including presidential races.

Portland, Maine’s largest city, adopted ranked-choice voting for mayoral races in 2011 and expanded it to city council and school board races in 2020. This year it was triggered to determine the winners of a charter commission race that included 23 candidates for nine district and at-large seats.