Why Philadelphia is an outlier in big-city mayoral elections

On the eve of the Democratic primary for mayor in Philadelphia, Rep. Brendan Boyle had something to say. The Democratic congressman, who had endorsed former city councilmember Cherelle Parker in the crowded race, decided to weigh in on how Philadelphians elect their mayor. “I wish to formally endorse changing our electoral system for the election for mayor. We need to move toward either [ranked-choice voting] or a top-two system,” Boyle tweeted. “Furthermore, we should allow all registered voters to participate.” Boyle noted that the winner of the Democratic primary traditionally...