In Trump's shadow, Republican suburban slide shows little sign of slowing

The last time Democrats controlled the government in Delaware County, a suburb of Philadelphia, the U.S. Civil War had just ended.

But on Tuesday, Democrats ended a century and a half of Republican dominance. In two other Philadelphia-area suburbs, they captured Chester County’s board of commissioners for the first time in history and seized control of Bucks County’s board of commissioners for the first time since the 1980s.

The Democratic gains in Pennsylvania, a state crucial to U.S. President Donald Trump’s election in 2016, suggest Republicans have yet to staunch...