Why Philadelphia Could Help Decide the 2020 Election

Philadelphia has been a Democratic bastion for decades. That doesn't mean the party can overlook it in the 2020 race.

The nearly 1.1 million registered voters in the nation’s sixth-largest city account for about 12% of all voters in Pennsylvania, a key battleground state. More than 800,000 of them identify as Democrats, giving the party a 7-to-1 advantage over the GOP, which is also outnumbered by voters who eschew either major party.

But as in other swing-state cities like Detroit and Milwaukee, the challenge for the Democratic presidential nominee—whoever it...