What is ranked-choice voting and why one state is using it for the presidential election

Even before a victor is declared for this year's elections, Maine will be making history.

The state will be the first in the union to decide the presidential and congressional elections through a ranked-choice voting ballot. Unlike a traditional winner-take-all plurality ballot, ranked choice voters are asked to list their candidates in order of preference and the victor is decided through a process of elimination based on those rankings.

Maine voters have become familiar with the process since they approved in a ballot measure in 2016 and used it in...